Needle felting newbie. Any tips or advice?

I just got into felting, and I have already made 3 siamese cat ball.. ornament... things. I plan to sell these on Etsy for some side income.

Does anyone have any good sources for wool, with a good selection of colors (preferably earth tones)?

What about tips in felting strategies for things like keeping lines neat, or blending colors together, fading them, general design layout planning, etc?

Pics of my first felt cat, the seal point: https://imgur.com/a/u6hJOgy