Are you ready to care for a turtle that may grow to 16" carapace length (common), or 24" (alligator snapper). Are you ready to provide a big enough enclosure for this size turtle..not to mention they're, for the most part, aqautic. Then theres the cleaning involved, and the feeding. Hatchling snappers are great little pets, and im not telling you not to get one, but consider the longterm commitment.
Common snapper hatchlings can be housed in a aquatic set-up, with water deep enough for them to fully submerge, but still reach the surface without swimming up. They require a secure hiding spot, such as plants or some sort of cave. They will feed upon small feeder fish, earthworms, insects, and cooked chicken. These turtles will bask, and a nice strong lamp will benefit them. In my opinion, they do well on a dark substrate, such as dark brown gravel. Snappers are not the best "handling" turtle, and large ones can and will inflict serious injuries. I personally do not recommend them for a first turtle. Something like a painted, RES, or even a musk turtle would be a good start. Good luck.
-Mike