How to play JJ before the flop depends of the table, and of course your position.
Beggining of the tourney:
Early position: I will raise 3.5 to 5 times the BB.
In Late position: I will raise the same amount used on early position, but i will call sometimes if nobody has already entered in the pot.
Late in the tourney:
Depends of your chip stack, if im in the red zone i will go all in with the jacks at any position. But if you have a stack in the yellow zone your play now will depends of the table, if the table is loose and has a lot of raises before the flop and u are at early position with your jacks, the best thing to do is just call and wait to push when someone raises at you. At a tight table u need to play this hand agreessive, so raise 3 to five times the BB with them.