[Ghazban]

Sometimes, you can fire again on the turn despite having missed. Some opponents at 6-max will assume any flop bet after a preflop raise is missed overcards and will call with any pair or any draw figuring they can push you off the hand later. The frequency with which you should fire a second barrel is heavily reliant upon your opponents and what their image of you is for a given session; you need to figure it out on your own.

Also, there is nothing you should always do (yes, that sounds weird but I meant it). You shouldn't always make continuation bets when you hit and you shouldn't always bet flops that you hit ('hitting' could also mean having an overpair to the board).

As an example of a time you could check a flop that you hit, say you had AdKd, raised preflop and got 1 caller in the BB. He checks to you on an Ac8h3s flop. You almost certainly have the best hand but there are few free cards that can hurt you (he's probably got 2-3 outs maximum on this sort of board). Checking behind encourages him to try and represent the ace that "obviously" scared you on the turn and/or river but also keeps the pot manageable when you've only got one pair (which is highly desireable if he flopped a set of 8s or 3s).