Beat over 75% of the games I have right now before I purchase any more new ones.

I find that when I get into the habit of buying new games, I drop all the ones I currently play to play that one. Sometimes I lose interest in the new game and try to start up from where I left off in the old ones and I end up restarting it cause I don't know what I need to do anymore. But by this time there's a new game out that I "need" to get, and the positive feedback cycle continues...