As a previous owner of two snakes, a ball python and a boa constrictor, I would recommend starting out with a ball python, they don't get as big, are mild in temperament, and are probably the hardiest of the large snakes.
When you go shopping for a python, ask some of these questions...
How old? (They don't grow all that fast, alot depends on diet, but the person should have some idea, and the size should somewhat reflect that.)
He or she? (Most people will not know, unless they've taken them to a vet. It is a science to sex those buggers, very few outward signs, and those are highly open to interpretation. A vet inserts a probe and by the distance it can be inserted can usually tell what sex the herp is. Mostly the question lets you know what the owner has done... taken to a vet or not?)
Originated where? (In other words captured in the wild or bred and raised in captivity. Prices can differ, wild being a little cheaper oftentimes, but they are not as docile or hardy as the captive bred. Also, I feel it is a matter or ecological health, I would only buy captive raised, I don't think they are ethically captured or shipped from the counties that they originate in naturally.)
Fed live or dead? (Most caring breeders, sellers, owners feed pre-killed rats, mice and birds. It is safer for the snake, more humane, and IMO keeps the snake slightly more attuned to feeding time vs. social time.)
A few suggestions,
1. Designate a box or paper bag as the dinner box. Place the snake in that box every time he/she is to be fed. DON'T feed in the cage. You don't want them striking at things entering their cage, like your hands.
2. Always wash your hands before and after handling the prey and/or snake. Salmonella can be carried by the snake, and if you handle a mouse your hand now smells like a mouse. Your snake's most powerful sense is smell, don't forget that.
3. Alcohol is your snakes biggest dislike. In the event that you were ever to be constricted upon (remember, they kill their prey by squeezing) open a bottle of rubbing alcohol up and either wave the bottle in front of the nose, or soak a cottonball and put near the nose. They hate the smell and will want to get away more than they want to squeeze your arm/foot/neck.
Most important, Have fun! They are incredible creatures. They are safe is handled safely. My 3 year old niece handled "Sweetie" often and we have many pics. "Sweetie" often nested around my neck, burying into my hair, or riding atop my head like a crown. I enjoyed his company and was the BEST pet to have in an apartment. No walking, No noise and little mess, and feeding time.
OK, I way overanswered your question, sorry
Julie