the goal of raising preflop with your premium hands is to limit the number of callers to 1-2, and to get your money in when you have the best hand. If you raise 4x a few times and the entire table calls, try 6x. If you do that a couple times and everyone calls, do 8x. whatever it takes to limit the callers.

A funny thing i notice, in games like .5/.1, i think raising too much (say 10xBB) preflop encourages more people to call at a loose table than raising less.