[Keiju]

One of my main problems with no-limit hold em' now is having a really good hand but losing all my money when someone has a slightly better hand, say I have 2 pair but someone else has a better 2 pair or I flop a set and someone flops a better one and also the same for a fullhouse or flush.
How would i go about saving my self money with this kind of hand, or rather what should i be looking for in these kind of situations if someone might have a better hand.
Only thing i can think of is to play passively, so as to only call other peoples bets or raises but playing this way gets you a crappy winrate and allows people to outdraw you too much. Or to play the good hands aggressively, maximixing profit and take the blows to your bankroll hoping to make enough with the aggresive style.
I would apprecitae any help on this