Before you start the taming, make sure your animal is well-fed and settled in. Then a few days of unsettling won't be harmful. One reader taught his snake to come to him, when he pats the ground. Just use your imagination, time, and treats. Many will learn to eat from your hand, or lounge around on your body, but that's about it.
Reptiles generally come and go as they please.
However, a good fence will keep turtles and tortoises in. Some lizards can be trained to walk on a leash. I have heard of iguanas and Savannah Monitors being able to do this. You would use a cat or rabbit harness for the purpose. Not only do they not understand the concept of a leash, the damaged shell can get infected.