Doing fan art on etsy is dangerous because copyright crazy corporations, like NBC, Bethesda, Fox, EA regularly comb through Etsy and demand items be taken down. Etsy has a 3 strike policy with fan art. After three strikes your shop is immediately and permanently closed. If you try to contact them you'll get their lawyer who WILL treat you like something he scraped off the bottom of his shoe.
Etsy will blacklist your name and IP address preventing you from ever opening another shop. I'm not saying don't open a shop on there, but know that your time on there is limited. You might get lucky and stay on for years, or you might get closed in three months. Depends on what kinds of fan art you're making. Eventually they WILL shut you down. And if you love doing your crafts as much as I did, you'll cry like I did. -_-