I just keep the phone close to my body so that no one else can see the screen. Also I sometimes close the cover and just hold the phone right up to her, since no one can really see that either. Luckily I've never really been caught taking pictures in class... I just got the girl a little suspicious of me
However, I have been caught doing things I wasn't supposed to... I was at a mall once sitting beneath some stairs and looking up girls skirts as they went up... didn't take any pictures, but I saw some great things there! The store the stairs were in front of called security on me because I think they knew what I was doing... so security came and told me to move

Oh well, there's always other spots!