Do you or have you done commissions? If so, how do you treat them? Do you have specific policies or stipulations, like getting half the money up front and half after it's completed? Do you make a certain amount of changes for a flat fee? Do you show the buyer your preliminary sketches? Will you make them anything they ask for? Don't you take commissions at all unless you know the person? Just curious how you handle this.
I've done commissions for years and only got shafted a couple of times. I usually email progress shots and make suggested changes, up to a point. (there is no satisfying some people and you certainly don't take another commission from that person)
I do almost all commissions and get my money upfront almost all the time. I do a simple email "understanding", and I guarantee they will love it when they get it and have only had one returned (amazon) in well over a thousand.

I do payment installments when requested, those are usually very young adults giving a group gift to a parent.

I show the final if the buyer insists, before I mail. The one I'm working on now gets that. I work around the requests for a wip by telling them I do the eyes last and they are creepy looking ahead of time, which is true!