a visor with (very, very) bright IR LEDs over your face could hide you from camera sensors; i've seen something like this used to defeat license plate scanners, and i know that LEDs have greatly improved power efficiency in the last decade, but i don't have any experience in this kind of thing. maybe someone can pick up this idea and run with it if it's feasible.

this wouldn't defeat something like gait detection though: http://www.geradts.com/html/Documents/gait.htm