How do you play hands like these post-flop

Party Poker (9 handed) converter $.50/$1 Hold'em

Preflop: Hero is SB with J[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">6 folds</font> UTG calls, MP2 calls, Hero raises, UTG calls, MP2 calls.

Flop: K[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, UTG raises, MP3 folds, Hero folds.

Final Pot:
UTG wins $4

What should I have done?
The experts say to raise pre-flop with pocket jacks in an unraised pot. But all too often I get overcards on the flop and someone bets out. They almost surely have it.