As I said, you want action from good hands(KK, QQ, JJ), not 3 J. You can not read the flop when someone has 3 J.....If 3 5 9 flops, you are dead meat, because you will bet huge on that flop, and he will just call probably, then you have to deal with the boat coming up as well.
However, if KK, QQ or JJ calls, and the flop delivers a set to one of those, then they will reraise you and you will see that they have the set, you fold and all you lost is about 600% of the blinds and not your whole stack.