Whenever i get pocket jacks i raise 5-7 times the big blind sometimes go all in when in position and have a table of callers. You have to play it more cautiously it seems like then any other pp. If the board comes 379 rainbow and you have someone betting into you there are 4 things to consider: 1. how much was called preflop, maybe indicating he has a higher pp. 2. he hit the set and trys to get full potential, if he makes around a half pot sized bet hes got you beat. 3. Is he trying to bluff the pot, or 4. maybe he hit the 9 and thinks you have just high cards. Rarely will a flop like this come and someone has a straight draw, but hey there are maniacs. I know there could be one million different ways a unfriendly flop could occur, but i hope this helps. Another thing, dont get to attached to pocket Jacks i always think of them as a middle pair and if i dont get a friendly flop then out they go unless checked. Remember your that much stronger if you can fold them then the guy who cant who will most likely get busted cause of it.