Good ol' fashioned saving, first off.. if you put a little aside starting early on, you'll have the money when the game actually releases. Example: I know I want the Last Guardian at release. It comes out next year. If I stick 3-5 bucks in jar once a week starting now, I'll have more than enough to buy it when it does release.
Aside from that- buy used. It's cheaper and you get a chance to see if the games you only sorta-wanted end up being crap and not worth your time before you buy. (Although it can backfire if a game gets rare and goes up in value instead...) Also, if you're in the US, signup to get Gamestop emails and wait for an E-rewards invite. Take online surveys, earn free Gamestop gift cards. (This is actually how I'm paying for the Last Guardian. I have card #2 on the way, if I get a third I'll have enough to pay in full and have leftover money. If I don't it's only $20ish dollars out of pocket.)