Unsure if this is the right board, so pardon me if i got it wrong!

I'm planning to sell a few sketch commissions soon, and since it'll be my first time doing through lioden, i would enjoy some advice on it ^^

But before that i have some questions, first how would payment in work? And how much do you think my art is worth?

I'm planning on doing stuff like these ↓, each character takes 30-40min


Thank you for your time!!