There're two ways to do that. One, you send people invoices with the payment through PayPal to their emails. Or two, you give them your email and tell them to send you a payment with the quantity you want through it.

I'd also recommend having a limited amount of slots so you aren't overwhelmed with commissions.

Thanks a lot, that's a help.
And indeed, I'd limit it to three for now so it doesn't interfere with Patreon monthly requests (5 sketch commissions and 2 B&W commissions)

I'm going to jump in with an important piece of information here.

You're asking about payment methods etc but that stuff is easy enough to figure out. There is one mistake that many artists make, starting out.

Think about the time, not the money.

What do I mean by that?

A lot of people start to do art and go "well, sketches for most people are $___ so...I should price myself like that."

No.

Think about the amount of time it takes you. Think about the energy and resources you put into it, think about the set up and clean up time, the external costs (photoshop? SAI? Tablet? etc.) and realize that an image is not just an image.

If it takes you 8 hours to do a color piece but you charged $20 for it, you're really paying yourself $2.50 an hour, which is ridiculous.

Your time has value. Your energy has value. Don't forget that!

Thank you, hun, I really appreciate you taking the time to write this C:

Gotta look out for my friends. ^^

Aaawww =(◕,´ω｀,◕)=

Don't forget the unspoken rule of art tho, what people are willing to pay for it.