Go for something big and sore and then if you get more then it won't seem as bad as the first. I got a 4 and half hour piece on my ribs in one go for my first, hurts like hell but so good to see it finished! Although obviously this approach isn't for everyone. haha.
The other posts are right though, make sure it's something that you really like and something that means something to you, ask yourself why you are getting the tattoo? Mine represents my family and reminds me of my grandad who passed away soon before I got it, It also reminds me of how lucky I am to be in the family and place that I am.
Goodluck on your decision to get one or not.