How do you date?

An interesting question!
Going to answer it all out of order and probably forget some.

Firstly, I've had 4 long term relationships (I'm now 30). 2 of them were meeting face to face and 2 were online.
I could write for days about online dating but that's not what your question is about, my personal takeaway is online dating is a bad environment for long term relationships. Short term, yes, but long term it's very difficult to get to the stage with another random person that you can start to work that "big picture" stuff out.
The end result though for both is the same in my experience if you're patient enough.

As for dating and making those calls, I found it really hard when I was younger because I would have a crush on someone and get as far as flirting, then dating. But really being younger I had no idea what I wanted or liked in a relationship and a lot of people my age didn't either.
Getting a little older now I'm able to vocalize much better what my goals are and try to judge if a person fits into that or not.
Daniel Sloss did a famous-ish bit on Netflix about a couple being like two partially completed jigsaws coming togerher and I think it's a very apt metaphor.
Being able to say "hey here's my life now and here's how I plan to fill in the gaps, do you like what you see?" and having the other person do the same is refreshing. Someone who can't shows a bit of immaturity in my eyes.
So when I was on my last dating slog over the pandemic and then some (my current partner I met on /r/r4r after I made a bet I'd not meet anyone from there, ironically) I was on the apps a lot and my mental health suffered a lot for it.
I went on a lot of first dates and struggled to be confident and charismatic, but I got better over time and when I did it became easier to get second dates and third dates, then I could start asking the important questions.

I think for me by date 2 or 3 I know I'm really into someone, but I could lose it in a heart beat without the trust and friendship if something comes up.
To build that friendship and trust takes a long time, months. I was dating my current partner for maybe a year and a half before I truly, truly felt comfortable with her (long distance though, so take that with a grain of salt).
The bond helps pad out the gaps. The annoyances, the bits of the jigsaw that don't match up. But it takes work and commitment to get there and it's hard to find that in online dating.

If I had advice for the next person reading this who's struggling with dating, it's try and be attractive. And not just physically. Do cool and interesting things. Get a hobby, do a sport, climb a mountain, learn the harp, knit a scarf. Having an amazing personality is a great start, but you want your date to ask you a million questions and be into you.

That was rambly, I might edit or add more tomorrow, it's late!

Context: I'm in my mid-30s, previously divorced (amicably - we weren't compatible as life partners but we're still close friends), now in a long-term relationship with a man I met on Tinder. Meeting him was a complete fluke, I think that dating apps are terrible, and I wouldn't do Tinder again to go on dates (I thought Bumble was kinda OK, I never tried any other ones). I dated both men and women in the past.

• I usually know if I'm attracted to a person fairly quickly. For me, it's rarely (just) about the looks, but more their personality, sense of humor etc. For my current partner, I knew on the first date that I wanted to get to know him better, but I've also had relationships where I was friends with the other person first and my feelings changed over time.
• For a first date, I just ask them out for drinks. I've done primarily online dating in adulthood and I find that this is a much better way to get to know someone than texting or looking at their dating profile. All these first date ideas like doing an art class or an escape room or whatever feel very gimmicky to me - I'm not looking to impress them with my creativity, I want to get a feeling for them as a person. If we like each other, then we can go on more dates to more imaginative places. But then again, for these later dates, it really depends on what the other person likes and what we have in common.
• This is a really complicated question! When I was younger, I thought every relationship had to be ride or die, together forever kinda thing, so I was 100% invested in long-term dating everyone. When I got divorced, I swung the other way a bit, and was really reluctant to commit to anything because I wanted to be sure that I wasn't going to get burnt again. It made for a rocky start with my current partner, because he was planning to move away for work and was also not very eager to commit to a long-term relationship. But I can say that I knew I wanted to date him long term after a few months of hanging out. He did end up moving away, and we had a weird few years between the pandemic and the long distance; we even broke up for a while. In the end, I worked on myself a lot to discover what I really wanted from a partner and a relationship, and he made some pretty significant sacrifices to live with me. Turns that once you're committed to each other, it gets a lot easier. Before, every small issue felt like a big threat to our relationship, but now it's comforting to know that a) ultimately, he's the kind of person I want by my side, even if he puts groceries away in stupid places and nags me about doing the dishes, and b) he wants to have me in his life and supports me in everything I do even though I'm annoying sometimes and don't do the dishes regularly, lol.
• Both! In real life, it was either people who were already my friends or people who I got to know through some shared experience (at a concert, convention, trip, dance class). I can tell you that for some reason, the cuban salsa classes where I live are full of late 20s-mid 30s singles. You get the feeling for who likes you really quickly, and if I were interested, it would be super easy to ask someone out, say, for a drink after class. For apps, see my answer re: dates - it's a bit weirder at first, but not that different after a date or two.
• For me, compatibility in values is by far the most important, and of course I have to like the other person for who they are. On the first date, what matters most is if I'm enjoying myself and if there's any kind of chemistry at all (and this is really hard to define precisely, as it's a combo of everything, from looks to personality to humor). I've had dates with hot people who were as interesting as a brick wall, and with people who were not at all conventionally attractive but were passionate and intelligent and made me laugh, and who I went on to date longer-term. People's main values are usually clear even before you meet them for the first time (or at the very least, after the first few dates), and then over the next few months as I get to know a person, it becomes fairly obvious if we're compatible long term and if I'm interested.
• Honestly, I think I have it figured out pretty well. The big two things I've learned: don't get attached to somebody just because they like you; and don't waste time on people that don't seem to be compatible with you. I still have a hard time with this last one, because I always want to give everyone a 2nd chance (since things don't always translate well in texts, or when you're nervous on a first date), but 99% of time, I was right about the person the first time around.

hello! I'd like to respond but I don't want to publicly oust myself, is that okay? I just don't want it linked to / easily searchable from my usual account.

I'm heterosexual, female, demisexual but not aromantic, currently in a decades plus, lifelong, monogamous relationship: answers may or may not be typical

How long does it take for you to know if you're attracted to someone (sexually, romantically, emotionally, shared interests, etc)?

For me, it's a whole Matryoshka doll layers of relationships.

a) Attraction due to shared interests/values/ideals/humour/stage in life, probably about an hour or so of meaningful contact/conversation/gaming/ice-breaker type situation. Pretty much a yes/no to "would I want to hang out more with this person?"

b) Friends, only after repeated regular contact (6-12 months+ for monthly meet ups, 3-4 months for bi-weekly meet ups, 2-3 months of weekly) -- all the time maintaining (a): if I discover that interests/values/ideals stray outside of a certain range during this time, then we're ever only going to be coworkers or long term acquaintances.

c) Emotional attraction is only possible from within, but not everyone among, group (b). I'd want nothing more than to hang out with these people all day every day for a whole week at a ski cabin kind of thing.

d) Romantic attraction, as in, I want to be dating this person exclusively (or even casually?), can only happen from within, but not everyone among, group (c). Due to the fact that these are already going to be my super good friends, dating them only casually wouldn't work at all.

(e) Sexual attraction - someone from group (d), and even then pretty much only in response to their sexual attraction. I've never looked at my partner and thought "dang, I want a piece of that". But I do often think "OH they're here they're here they're here! Let's go hang out <3" which, a lot of the times their idea for hanging out includes something sexual, and we have a good time.

What do you like to do when you date and does it change depending on how many dates you've been on or how well you know the person?

N/A, or regular good friends things, since they're going to be my good friends. If we're dating then there's a whole range of good-friends things that normal society frowns upon between good friends, especially if they have romantic partners, or would be awkward to explain to future romantic partners. Those things. Such as sleeping on their laps or staying the night in the same bed or chatting with them from the shower while they brush, tend to be frowned upon as mere friends. Even things like automatically ordering two dishes so we can share seem to be much frowned upon by dating partners :\

Once you start dating someone, how long does it take you to understand whether you want to date the person long term or whether it's not going to work out?

I would only date them after carefully considering the long term possibility + the probability of us remaining really good friends if the romance falls part. So kind of the reverse of what this question is asking.

Do you only date people you meet in real life or do you use dating apps? How do you approach going from stranger to dating them?

I would only make friends using apps, and be very clear that I'm looking for friends. That would be my dating strategy because that would be my potential dating pool.

What's most important in deciding whether you want to date someone? Do they need to have an interest in activities you enjoy, shared values, emotional intelligence, a certain kind of humor, or something else?

For someone to become really good friends with me, they would already fit into a rather narrow category of interests....we don't need to have all the same interests, but at minimum enough overlap that we could do the same things together at least part of the time. Same values, definitely -- and after learning from youthful experiences, professed values don't count: they have to be completely owned, well demonstrated, automatically expressed values. And since I an monogamous, that they are as well would be a deal breaker sort of thing.

Is there something you don't understand about dating and want to share your frustration?

My frustration with sex in media... It's like, if our culture were obsessed with Noodles, and every media must have Noodle Scenes, where the lovers begin their relationship or culminate in a scene where they go out for / make noodles together. And it often doesn't really tell you why their sharing noodles contribute to their relationship at all. Nothing like, John ordered this for Mary because he knows she doesn't eat X, or Sue saved all her X from her bowl because she knows Jane loves them best, or Henry went through heck to get reservations at this exclusive noodle bar and meanwhile Dante convinced a retired noodle chef to cook for Henry. Nothing. Just some reaction shots and satisfied eating faces and slurp noises and chopstick motions, and we're supposed to be convinced some kind of magic chemistry or intimacy was achieved.

I love noodles and I can understand the desire for and carnal reaction to noodles better than I understand sexual attraction/excitement, but wouldn't you be upset and bored by the gratuitous inclusion of noodle scenes?

I am married but going to participate as it's a fun topic.

How long does it take for you to know if you're attracted to someone (sexually, romantically, emotionally, shared interests, etc)?

Attraction can be more or less instantaneous, in my experience. I am more of a "spark" guy than a "see where things go" guy, if that makes sense. While it's certainly not solely physical, even beyond dating, I can think of only a small handful of instances in which I upgraded my opinion of someone's attractiveness after the first, say, hour of knowing them.

What do you like to do when you date and does it change depending on how many dates you've been on or how well you know the person?

It has varied, though like another commentor I sort of went off of the twee "painting date, so quirky!" stuff. Only in very specific circumstances with very specific people did I ever do anything beyond drink/coffee/lunch type stuff for initial dates. Once you've been dating someone exclusively for a while, I feel like you're basically just doing regular people stuff together. "I'm going to the farmers market, want to come?"

Though I suppose if your default is to do nothing (which I say without judgement), then doing anything would be special.

Once you start dating someone, how long does it take you to understand whether you want to date the person long term or whether it's not going to work out?

Mm... I think you can tell within about 3 dates, on average. Really, you can often tell faster, but you should know by the end of the third. That's assuming you started as strangers, of course. If you're actively working to understand them, it should take about that long to get a sense of the person's values.

Do you only date people you meet in real life or do you use dating apps? How do you approach going from stranger to dating them?

I did both. The apps were primarily for hooking up, I found, and there's absolutely no replicating an in-person spark.

It's basically the same process as making a new friend. You meet someone, have an initial connection, and you decide to do a thing together. If it's great, you decide to do another thing together, and the cycle continues until you've reached some sort of equilibrium, whether it be "we're going to keep this casual" or "let's get serious" or whatever.

What's most important in deciding whether you want to date someone? Do they need to have an interest in activities you enjoy, shared values, emotional intelligence, a certain kind of humor, or something else?

For serious commitment, physical attraction and shared values are basically it, as long as there are no deal breakers in the other catégories (perhaps a terminally bad sense of humor or completely handicapped emotional intelligence.)