If possible, keep the food off of your body entirely. Put it in a dish nearby, and actually walk to get it after each click. Work on attention from the very beginning, so the dog learns to focus on you instead of the treat. If the dog is staring at the clicker or the treats, don't click until he's focused on you again. The third key to clicker training success is using the clicker correctly.
Timing is everything.
Most people click late. If your timing is off, the clicker becomes a treat marker, not an event marker. Like any mechanical skill, it requires practice. Have a friend drop a ball, and try to click just as the ball hits the floor. The sound of the bounce and the sound of the click should be simultaneous.