I play cash games,tournaments might require something different. That being said: JJ is a premium hand. If you are first in always raise. You of course should have a standard pre flop raising size so whatever that is use it. I play six max and do 4xbb but whatever you use raise that baby up.
If someone has limped in front of you raise it up and add one bb per limper. So if I'm in cutoff and utg limps in front of me I'm raising 5xbb.
Now if you are facing a raise in front of you it depends on who raised and what their position is but generally I'm 3 betting here. There is a good chance that you can take it down pre flop and if you do get called are at least playing a pot in position with the initiative. If I get 4 bet/shoved on I'm folding unless they are a known lunatic or they are extremely short stacked.
Post flop if they check it to me I'm firing a c bet on virtually any board. I represented strength pre flop so I'l continue to do that. If the flop contains over cards and my c bet gets called I'm going to probably shut down on the turn and river. If I can I'll check it down for showdown value. If my opponent bets the turn or river strongly I'm probably folding at this point. If I get check raised at some point I'm going to give them credit without some real strong reads.
IF the flop contains no over cards and no real dangerous draws, go to value town. Keep betting. If you get check raised you can probably fold (Baluga Whale's theorem FTW) otherwise if you think they can be calling you with a number of worse
hands bet and extract value.
All of this could change if you have some really good read on a specific opponent of course. Just make sure you don't over think it and out level yourself.
That's usually how I play JJ. As always I welcome someone with more knowledge correcting any obvious howlers in my ideas.
GL