Most important parts before making the decision is keep a pet snake: 1. Are there available live rodent feeders of all ages (ie pinkies) at your local pet store in the event you must feed live? 2. Is there an experienced snake vet near you or are you willing to travel to one? 3. Are you looking for a pet that you can take outside and show off, handle the snake hours on end or numerous times daily?
If the answers to #1-2 is a no, or #3 is a yes, a pet snake may not be the right pet for you. Even pet lizards that are vegetarian or omnivores will get stressed out from too much handling, and they need more vet care than the average pet snake.
If you are truly ready, then do your research thoroughly to narrow down what you want: active during the day or nocturnal? Heavy bodied or slim? Keeled scales or smooth? Easy to care for or a challenge/less likely to forgive mistakes? Display pets or tolerate handling? Tall tanks (arboreal) or not (floor space required)? Size limitation? Captive bred or import?