Advice for playing an under-boat?

Can anyone give any general advice for this situation? I would say that for a noticeable number of my under-boat hands -- maybe even 20% -- I get stacked by someone with the over-boat.

For example, if I have a low/mid PP, and flop a set, I am usually check/calling the flop -- maybe even the river depending on how aggressive villian's flop bet is. If anything else on the board pairs on the turn/river, I am even more confident, planning to be all-in on the river. Should I be more aggressive on the flop unless my set is the top card showing? Should I just accept losing an occasional stack this way? Folding to a big re-raise on the river when I've made a boat seems abjectly pathetic, since I occasionally see missed draws bet that way.

TIA.