Outplaying your opponent in my opinion is making them make mistakes combined with being able to accurately estimate their range and play optimally against that. This could involve bluffing because you know they are weak or checking to induce a bluff when you have the goods among other scenarios.

Some main post flop skills:
Continuation betting at the right time
Double barrelling at the right time
Bet sizing
Extracting value
Adjusments for number of players and position
Having a plan before you start committing yourself to the pot


This list can go on and on really but there's some ideas