Position is a big defference in NL. The better position you are in, the better your hand becomes.

Build pots with you have a big hand (trips or better). If you have trips, bet on the flop and turn.

If you think you are ahead in a hand, bet at the pot to avoid someone hitting their straight or flush.

Middle pair is garbage with more than a couple people in the hand. Play small pairs for sets. If you don't hit a set on the flop, put yourself into a check/fold mode.

If you have raised pre-flop and are in the flop with no more than a couple people - continuation bet at it, no matter what you have. Bet the pot, if someone calls and you still have only ace high, you are probably loosing unless someone is drawing.

Don't bluff until you have a few thousand hands behind you.