Here are some links to websites that provide their opinions on handling and taming chameleons.
http://chamworld.blogspot.com/2008/01/handling-your-chameleon.html
http://muchadoaboutchameleons.blogspot.com/2012/04/to-handle-or-not-to-handle.html
These two are pretty good links.
There's also a blog by Psychobunny on THIS website you can use. I'm not sure which link it is, so you'll have to dig for it.
My own personal experience is that they need TIME and PATIENCE, and lots of it. I started by letting him see the food AND my hand. Put your hand in the cage, and place the cricket/roach/worm/whatever near the chameleon. Do this for a few days or weeks until he learns that your hand drops the food into the cage. He will probably stop hiding from you then.
After he no longer hides from you, then you can hold the cricket/worm/roach/whatever by the tail end, and occasionally squeeze it so it wiggles. Hold it from the chameleon's face around 3-4 inches away, farther if the chameleon is uncomfortable. If he wants the food, he will zip it out of your fingers.
After he is USED TO taking food straight out of your hands, you can start feeding him like that all the time and get him used to it even more. (My chameleon doesn't even eat really unless I hand feed him).
Then try the "bridge" method. Hold two hands out. One is your hand, palm up, and the other is another hand, holding a bug BEHIND (farther away from chameleon) your palm up hand. The chameleon will probably have to walk ONTO your hand to get the food if you hold the food far enough from it.
Do this often enough and it will get the idea that it is safe to walk on your hand for food.
Once he starts coming onto your hand for food more, or even standing at the front of the cage and waiting for food, he knows you are there to feed him and he trusts you a little bit.
Sometimes they will come out onto your hand when there is NO food, just because they're used to it. They expect a treat eventually though.
I always give my grumpy one a treat for coming out and sitting on my head or hanging in his tree.
