I personally wouldn't recommend a GTP as a first snake, if only because arboreal species tend to have slightly higher care requirements and slightly more touchy temperaments than many other pet snakes (though they're by no means as aggressive as some people make them out to be). I'd suggest getting used to keeping snakes by starting with a different species first. A cornsnake or one of the Mexican kingsnakes is my personal recommendation as they're very easy to care for and are very docile, but ball pythons are popular too. That's just my personal recommendation.
The place you need to go to learn more about GTPs is
http://moreliaviridis.yuku.com/
Online breeders are the best for GTPs. Above all, DON'T get one that may even possibly be imported or wild-caught. They are extremely snappy, usually riddled with scars and mites and possibly diseased. Captive-bred GTPs are not quite as bitey, but still it's not a snake for anyone afraid of being bitten. You just can't put your hands in the cage after dark, when they're in hunting-mode. And above all, don't get a baby. They are extremely fragile when they're born and cannot be safely handled until they're about a year old, or you risk damaging their tiny little spines. A juvenile at least a year old would be best for a first GTP.
Good luck with whatever you decide to do!
