Well, firstly, make sure that any tattoo shop you go into looks clean. That's a pretty good sign that they take their job seriously and, in turn, take pride in their work. Just take a look around and let them know that you're not planning on getting inked that day; you're just looking. Ask them if they have portfolios that you can look at - those are the best way to determine how skilled the artists are because they're pictures of work that they've actualy done. If a shop only has flash on the walls, but no personal work on display, that's not a good sign. FInally, if you find someone who does good work and has a style that you like, talk them about what you're interested in getting done to see if they feel like they can give you what you're looking for. And agree on a price BEFORE you start getting inked.

Hope this helps.  =)