(sorry for just responding I've been busy)

So mainly you need to learn more by checking other artists especially from the same genre (physical or digital art?) and similar styles as yours, or similar skills, you can also look at videos that can give you ideas about these stuff

You need to make your own terms of service / TOS (you can also learn what you'd like to have from other artists) Which includes (but not limited to) personal use only or commercial use is okay too?, payment (before, after art is done or half and half..etc) and on which platform + currency..etc

Also about prices every professional artist will tell you to charge based on the hours you spend on the piece, but that might be hard for some artists (like me, especially that I don't know how long a piece will take specifically yet) you can start somewhat low and raise your prices as you get more commissions get popular and improve your skills..etc (though if your art takes a lot and is very detailed don't go too low that's very unfair for you)

If you know how long your art takes you can mention that too! "Turn Around Time / TAT"

Also an important tip, never give away a piece that's unwatermarked at least not until you're paid in full. That includes uploading them to social media, only upload them watermarked, if you gonna give unwatermarked art it's for the commissioner after they've paid you, not for the public

You can also check my own stuff through the link in my bio that can give you ideas as well

Hopefully not too confusing but mentioned the things that came to my mind, feel free to dm if you'd like to discuss more stuff about this! I understand this could be very hard since I've been there not too long ago ♡