Playing the flop with two overcards is a topic that most authors would say requires experience to do correctly. Nevertheless, the conceptual basics are pretty clear and can be grasped by an astute beginnner.
It's impossible to make a one-size-fits-all prescription because so much depends on the specific texture of the flop, what overcards you hold, what backdoor draws you might have, etc.
But some things you should consider are:
- Most importantly, how much money is in the pot and what pot odds does it represent?
- Second most importantly, how many opponents remain in the hand?
- What is your estimate of the probability that, if I turn one of your overcards, top pair will win the pot?
- What is your estimate of the probability that an opponent will make a better hand to beat you? This is where level of coordination comes in -- is the board two-suited? Does it have high connectors that would make someone a straight or two pair?
- What sorts of backdoor draws do you have?
There's no single answer but just to take an example, AQo on a moderately uncoordinated flop (rainbow, no three-to-a-straight) with several opponents might be worth 3-4 outs, between 50%-66% of the six raw outs. (Keep in mind everyone loves to play aces, therefore there's a decent shot that you're reverse dominated and hitting your ace will give someone else two pair. So even a 50% discount may be not enough.) You therefore need between 11:1 (47/4~=48/4=12) and 15:1 (47/3~=48/3=16) to go ahead. If you raised PF as you should have, you might get those odds.