from what I've seen, people post a pic of the YCH base, and in the comments there's a comment of the starting bid and people go from there, and then another comment for where they go if they just want to talk about the picture, and there's usually also an Auto-buy price if they don't want to bother with a bidding war

What would be the usual auto-buy price?

They charge their Auto-buy based on the price of a full commission, I think, which varies from artist to artist. I don't think I'm qualified to try and price your art work though lol

Normally people do a ych pic (rough sketch of what they're auctioning)

Then under it the restrictions.

Under that the "sb" the lowest price they can go.
Mi the lowest price they can raise by
And auto buy. Which is just the price you pay to end the auction instantly. Keep this about as high as you think the auction would reasonably go before the quality starts getting outweighed by money being paid.

Then In the comments just have people respond to your comment so you can keep track. "Bids go here"

Maybe make another one for feedback and questions.

Thanks a lot :D