On my quest to self-publish, I have just learned a very valuable lesson. When hiring someone for cover art, ASK TO SEE SAMPLES FIRST. Just because someone works as a graphic designer (!) and his mother-in-law (a distant relative of mine) says he's good, means nothing.
I asked him for a picture of a pretty, slender, short-haired 16-year-old girl with wings. Even told him her hair and wings are gold, and her skin is Anglo tanned. I had done a couple of sketches (probably should have sent them to him) but the best you can say of my art is that I'm a decent amateur.
What I get is a gray-faced robot with a cape. I am not kidding. The skin on this creature was gray. Its flat yellow hair was in a pony tail. The torso was a featureless rectangle, the arms and legs rigid cylinders. The wings looked like a cape - there were no feathers, and absolutely zero understanding of the structure of a wing.
I thought it over for a few days - he wanted to be told what I wanted to change, and I couldn't think of a polite way to say "Everything." So I told him (having said earlier that my husband was in charge of the budget and would have to clear the $100 we'd agreed on) that my husband didn't think the art was worth a hundred, and I was sorry to say I agreed.
I never heard from the guy again. However, his mother-in-law (my mother's cousin, I don't know if that's once removed or what) Facebooked me that it was a shame I hadn't asked for samples first, so he wouldn't have wasted his time. I should have let it drop, but was so completely apalled by this dreadful, amateurish piece of art that I replied, "Didn't look like he wasted much time. I drew better than that when I was twelve." Well, she got angry - can't really blame her. I think she's unfriended me. I don't really care - I've only seen her a handful of times in my life and would be hard-pressed to pick her out of a crowd.
The moral of this tale is: When commissioning art, even if it's from friends or family, ask for samples first so you know if you're offering your hard-earned money for something you could do better yourself. And actually, better not to commission friends or family, or anyone you'll have to see again, because if you have to fire them, it'll ruin the relationship.