I have a love-hate relationship with JJ.
Basically, I want to see a flop when holding JJ. I don't really want to get it all in pre-flop, espaecially early in a tourney. There are too many people who will call off with any ace.
I do want to bet pre-flop to reduce the field and build a pot. But if I've got 20 bigs or more it usually won't be a shove.
That said, it of course depends on a nuber of things:
1. Position
2. What was the action leading in to me.
3. What are the tendencies of those left to act?
For example, if there are LAGs left to act, I'll want to raise it a little higher to build the pot.
For TAGs, I'll still raise, but a little more conservatively.
For Nits left to act, a small bet into them is preferred. They'll often fold to the slightest show of aggression when they aren't holding premium/made hands. And since they're likely to come back over the top with a strong hand, I can easily fold or call depending on the villain.
When the flop hits, I'll often want to C-Bet, even if there is a queen, king or ace on the flop. I'll then be looking at a person's FC stat here to help me understand what a call might mean as well as their 3B stats to guage any re-raise.
But with a dry board, free of QKA, I'll be betting at least half-pot, but more likely closer to pot size. Basically, if villain wants to see another card, theyr'e going to need to pay a premium. (Usually, you'll take the pot down here...which is fine).
Late game with 10BB or less, JJ is an easy shove pre-flop or a shove on the flop with a dryboard with no QKA.
Do look out for QKA plus straight and flush draws on the flop. Wet boards can become very grim, especially if playing multiway.
But at the end of the day, JJ is very vulnerable. Lots of people will say "there is no correct way to play Jacks" (and there is a funny video of it being played "wrong" in a dozen scenarios (all of which *seem* right, pre-flop).
JJ should be treated as typical pocket pair, but the urge to shove should be resisted from early position and with > 20BB.
Cheers,
JT