[VanVeen]

Good post. If you're not willing to put all your chips in the middle on this flop, don't bet - check. If you are, bet. When you should do one or the other is player dependent (is he capable of bluffing/semi-bluffing? what kind of hands is he willing to payoff with? etc.). After you've bet the flop you cannot fold with as much equity as you have vs. his probable range of hands, and just calling (as Paluka pointed out) is going to allow you to make a more costly error on the next street if you don't improve.