In my experience, the general tactics of playing with the pocket pair JJ:
1. Raise from any position in the amount of 3bb or call the opponent's raise. If there is a 3-bet, then fold.
2. Play better against one or two opponents. If three or more players are playing on the flop (not counting you), the pocket pair JJ loses its power.
3. In the presence of overcard on the flop (A, K and Q) it is necessary to make a check, call or fold on the raise. With a safe flop and no raises-you should play aggressively, squeezing opponents out of the game.