Leopard geckos are somewhat fearful and quick when youngsters, and normally they should tame down as adults. However, if they aren't handled, they might remain cautious. You can start taming it as soon as you are sure it is eating and not stressed. First try spend sometime near the tank, go near it to observe him, etc. Then you can throw feeders near him, or generally in a way he can see you giving the food. Then you might want to start handling him. You shouldn't handle him too much at first, just picking him up to put him elsewhere when cleaning the tank is considered handling for now. He will be squirmy, but after a while he will realize you are not a threat. These geckos can drop their tails, but they are very reluctant to do so. But to be safe, don't pick him up by the tail. After sometime you can start handling him lightly, that is, just put the animal on the palm of your hand and/or hand-walk it. It should be fine. This should be done at the opening of the cage, to prevent falls and escapes. After some time, you can handle it farther from the cage. After a little more time, try to touch more other parts of its body. In 2 months at least it will have become tame. Some geckos become really tame, that is they don't object even if you touch them near the eyes, on the base of the tail etc, while other still go on alert when they think you might touch them in a threatening way. The most reliable indicator that your gecko is no longer stressed by you is feeding just after handling. That means the animal feels safe with you. Some geckos also eat outside their enclosure or in a smaller enclosure, but this is rare and those which do it don't eat every time outside, mostly when very hungry.
With this method I have tamed many leopard geckos. Hope I was of much help.