for example something like big slick, or KQ (suited most likely, but occasionally unsuited). if the flop comes something like 2 7 4, what should i do? keep playing agessive as if i have a middle pocket pair (eg pocket 7s in this example), or fold if somebody bets/raises?

thanks

I would recommend that you learn about something called the Continuation Bet (cbet).

A continuation bet is a semi bluff made after you have raised preflop and get at least one caller. It is often correct to follow up your pf raise with a 1/2 pot to full pot bet on the flop (the best bet size depends on a number of factors). 2/3 time the flop will miss your opponent, so it is profitable to make this play as most of the time your opponent will have to fold. If they do call you still have 6 outs to improve to a better hand.

Obviously there are situations when it's not right to use a cbet and also times when it is. If you use the forum search on the left hand side and search for 'cbet' you will find loads of hands posted by people where cbet was / wasn't appropriate.

^Yes - but keep in mind a lot of people will pick up on that betting pattern if you raise pre-flop with something like A - K. I almost immediately put someone on A - K if they've raised pre-flop, bet a low flop and then checked the turn when nothing came.