I agree with the above. You want to take at least one shot at the pot after raising pre-flop. However, if it comes with an overcard and someone bets strongly into you, he's probably got it and you're safe to fold. There are tricky situations where he might be betting a draw and you want to raise the flop, but you need to have a good read that your opponent is capable of this kind of bet. (Some players habitually bet flush and straight draws.)