The important thing is to choose the right species. Many people start their kids off with a green iguana. In my opinion, iguanas are not an appropriate species for inexperienced reptile owners. They have very stringent environmental and dietary requirements that are difficult to reproduce in captivity, leading to poor health, stunted growth, and a short life span. A much better choice for a budding herpetologist would be my personal favorite, the corn snake.
Corn snakes are native to the United States.
Due to their ease of breeding, corn snakes are inexpensive and available in a rainbow of beautiful colors and patterns. In addition, they are generally quite docile, although very young specimens may be a bit flighty. They are relatively small snakes, topping out at about 3 to 4 feet in length. In addition, they are easy to feed and keep, without the many complications of vegetarian lizards such as iguanas. One problem some folks have with such snakes is the fact that they are usually fed mice.