It's hard to deal with a player who raises a lot. In order to do, you're going to need to figure out (or guess) whether they're “slippery” or “stubborn.” This can be hard if you're playing virtual poker.
Suppose you're playing a free virtual poker game on the internet. There's a player who has raised before the flop many times, so you know he's raising some marginal hands. If you think the player is slippery, go ahead and reraise him with a marginal hand yourself, like 55 or 67s or what have you. Since he's likely to have a bad hand, he'll usually fold.
*If a player is stubborn, it means they won't throw away their junk hand. Against this player, just wait for a real hand. They'll raise, you'll reraise with your big pair, and you'll get all of the chips against their mediocre hand.