First, realize that chams generally are suspicious about other creatures in their worlds. Its not personal, its just how they are hard-wired as it is a survival adaptation. Also, chams are very territorial. They want to defend their space from intruders. You are an intruder. What you start off doing is to teach him that you are a regular part of their captive life, that you are not a threat, and that you are fairly predictable (daily routines with the cage, feeding, watering, cleaning), and that you can be a source of good things. At first, in a new home, new territory, new daily routines are all threatening. As babies they are not as protective of their turf, but as they get older they are more so. Even if he was scared early on, you can teach him to trust you. Chams are also individuals so some will become more "social" than others. Its very hard to predict this and handling more or less won't necessarily make a very touchy cham more friendly.
First, get your daily cage chores on some sort of schedule....lights, watering, adding food, etc. Chams hate change and trust routine. Don't keep up setting him with constant adjustments to his cage...that's his turf. Give him visual cover and some privacy from commotion around the cage. He can be less defensive that way. When he's got his little personal routines down (basking, hunting, drinking, patrolling his territory) you can start offering him favorite feeder treats by hand. Maybe start offering them in a hand held cup if he's scared of your hand. It takes patience, as chams are not rocket scientists.
