Reloading after every instance of firing. Even if I only used 4 shots from a slow reloading LMG.
Looking in corners for items. Even in games that don't have anything there.
Stocking up on healing items that I'll never even end up using, even on the final boss. I stockpile and never even use my stockpile, even in the last chance I have to use it.
Setting sound effects volume to lower than the rest. I don't need to hear the SE really loud. The music and dialogue are more important, and some games make your gun/engine REALLY loud. *glares at racing games*
Playing offensively. I never block, even in fighting games.