It really depends on the animal. Some will come out all the time on their own, others will throw a fit and get really upset if you even get close. Most of them will fall somewhere in between. Many chameleons will learn over time that you are a source of food and they become less weary of you. Some will even start to come out of their cage without any "taming exercises." (I had one that one day just decided he would grab onto my arm and go for a ride. I also have one that acts like I'm coming to murder him when I come within a few feet without the food cup.)
I always suggest trying hand feeding first and using it as a way to draw them onto your hand. It's a good idea to make sure that a handling session always ends with something they like (outside sun time, a favorite food item, a shower, or whatever your chameleon likes.) Never force handling unless you absolutely have to. The more pleasant the experience is, the more likely they are to get used to it/start coming out on their own.