When stacks are still deep, like 30-40 BB's, I like to see a lot of flops, but I try not to get married to any hand, because there's not a lot of pressure to get stacks in right away. Rather, it's best to just chip away slowly until you get to the push/fold period.
Most importantly, though, you just really have to adjust to your opponent. If he is limping his small blind a lot, you should raise your small blind. If he is pot-betting every flop, try to trap him. Playing your opponent's tendencies is probably the most profitable thing in heads-up.