How do I fix my (stupid) use of excessive punctuation?

In online forums I use far too many punctuation marks. I especially use dashes - to separate clauses that don't need a dash (and sometimes I'll add brackets like this because, well, I dunno). And sometimes I'll start a sentence with "and" when it doesn't need to be there. My comma use is wild and uncontrolled, but I feel it's a bit more controlled than these other marks.

Importantly: I do not care how other people use punctuation.

But I would like to try to fix, or perhaps just improve, my punctuation use. Like the way I just start a new paragraph at random.

I feel like my posts are the same as those flyers that use 7 different fonts, with bolds and underlines and italics (and combinations of them), and with some words in red and some in green and some in black and there's no rhyme or reason to it.

I do like a casual tone but I feel that I go far too far in the informal direction. English is my first, and my only, language. (I love Europe, but I am a bad European. "Please look after our star" we said, and most of us said it in English because most of us who said it don't know other European languages)

Do you have any advice? I'd be interested to hear about books, or videos, or courses, or podcasts, or anything at all that can help. I'd even pay for this. But not Eats Shoots and Leaves please