My strategy, which has worked pretty well so far, is to buy whatever game that I can find in mint condition, at the lowest possible price.
Now, I know what you are saying, "DUH!"
But let me give you an example:
I ONLY collect games in complete, MINT (or as close as possible) condition.
Right now, I could care less what the game is, just as long as it's cheap, and in complete, MINT condition.
Within the past 3 months, I have picked up 8 games, for a total of $390.00 (including shipping.)
When compared to the price guide, that's one hell of a savings. And no, the games don't suck either - KOF '97 for $90 was a great find, and the most I have paid for a game thus far.
I guess my point is, I'm not in any hurry for any particular game, so I get what I can, for how much I am willing to pay.
At this rate, I will probably have 40 games by Christmas, and I would put the ones that I have now up against anyone's when it comes to condition.
Now here's the rub - I collect games for EVERY console system (except PSX, XBOX and PS2). Imagine how hard it is on my wallet to do that!!
Take care & good luck,
Steve