that's where the raise and hand selection come into play. if you make it painful for them to call with crap, and punish their poor play, you'll find them less likely to call you with junk hands.
another thing, if you're playing on the 10/20 no limit tables, it's pretty hard to get away from horrible players. it's not uncommon to get kings or aces cracked by a reckless player who pushes all in with a dreadfully inferior hand and gets lucky. if you get a chance, you should try and learn no-limit on the 200/400 NL tables. they play a lot more responsibly. just check the pot stats like NME said, and try and find a full or near-full table, small pot average, and just play really solid hands.
good luck