It's not so much a 'trope,' but my writing style tends to naturally mimic whatever (good) author I happen to have read most recently. So I bounce around between wannabe-Tolstoy, wannabe-McCarthy, wannabe-Dick, etc. It's always a trip when I look at my old stuff -- I can always tell what book I was reading at the time.

BUT TROPES THOUGH

I have to constantly fight the [url=http://tvtropes.org/pmwiki/pmwiki.php/Main/FiveManBand]five-man band[/url] trope, especially when roleplaying. Also [url=http://tvtropes.org/pmwiki/pmwiki.php/Main/ConservationOfNinjutsu]Conservation of Ninjutsu,[/url] but then again, pretty much everyone conserves ninja. 

I tried to submit a pair of opposing tropes a while back, because they really should be tropes -- "Take the money and run" versus "Leave the money and walk." You know that scene, because it's all over the place -- the hero and/or badass just leaves the money on the table and walks out of the room, and later the bad-guy-slash-coward furiously tries to scoop it all into their pockets while fleeing after his or her defeat.