There are several other people asking the same question here. Generally most people suggest a leopard gecko or a crested gecko. Bearded dragons are larger and more responsive pets. That also means that they need a bigger enclosure (36" length minimum), and make more of a mess when they poop. All of these reptiles can live 10-20 years which means that you'll still have them when it's time to go to college. You don't have to worry about what to do with them now, but it's worth thinking about if there's no one else in your family who's interested. Many dorms don't allow any pets at all.
To figure out which reptile may be for you, google "[type of reptile] care" and read a few caresheets about each reptile. This is how I decided to get my first reptile, a leopard gecko (I read all the reptile caresheets at a big petstore and got rid of anything that seemed too involved and only had one type left). Most of the information about each reptile will be the same, but there will be some differences. Read the posts in the specific forums here about the different reptiles you're interested in (find a bearded dragon forum to read about the beardies). Ask specific questions (many of these questions have been asked already and answered, so look before you ask). That should help you decide what to get.
Aliza
