Thats some beautiful shit!
Its always better to just take the initial request from the person and then finish it and present it without further input imo
or you can tell them upfront that the more revisions or changes they make the more $$$
Yeah I have an entire Terms of Service that is attached to each invoice I send to every client with the details of what they're allowed for the commission type they've purchased, as well as an explanation that they have to pay for revisions beyond their allowed limits at an hourly rate. They didn't go over, but certainly used every bit they were allowed within their limits haha.
Saying that though I find that it's actually more useful to hear what they want earlier on. I don't want to finish something and then have them ask for revisions as it makes it more complicated to fix the closer to completion the piece gets. However I do actually put my foot down when it comes to some requests - if they ask for something I know wont work then I will be sure to tell them its a bad idea. If they still want it then they will get it....I just probably wont post it anywhere if it makes it ass ugly haha. Naturally there are just some clients who want more control than others though which can be fine. I think being tuned into communication is integral if they are.
Speed paint thing I did for the winner of my charity art raffle I held in December.
....if this is too nsfw I'll put it under a click through link. Wish I could spend more time on it like 99% of my works...surprised how much I enjoyed working on this despite the characters original design.