do those detective tricks.
tell your family don't go into your room, put a piece of paper between the door and the door frame. do the same for drawers. remember to make it not noticable. if someone open it, you will find a piece of paper on the ground instead.

for your comp, keylogger is a good idea

don't walk around while listen to music. or something that block one of your senses. use your gamer instinct damnnit :P