this is what I do, dont know bout you guys, but at my theater there is a separate ramp for going to the bathroom vs. the one where they rip studs and whatnot.i just walk past the box office, go to the bathroom, grab some food, and look at the big board that shows all the movies above. then i just walk up that ramp and confidently stride to the theater.
If you are super young (im 16 and can pull off being 17, so they aren't suspicious) go into w/e theater it is, and find some older people (older than 18 too, like old enough to be your parents) and sit RIGHT next ot them. That way when they look around, they are 100x more likely to overlook you because you look like you are with more mature elders. This only works if there are 2-3 max. if you have a bigger crew, just divide and conquer. NEVER sit in a huge group of 14 year olds, you will get busted SOO quickly.