My own experience with the Poker Stars .25/.50 is this:
A ton of people limp with Ax, especially when it's suited.
A ton of people limp in with suited connectors (or non-suited connectors for that matter.
A ton of people limp in with any kind of low to medium pocket pair.
Some people limp in with absolute crap.The one thing that you'll notice is not on that list is that there are fewer people who limp with Kx unless it is two broadway cards, and almost nobody limps with Qx unles it's QJ or QT.Now maybe it's a bad habit, but given the kinds of preflop hands that I've noticed people generally limping with, I tend to raise with JJ out of the SB.If an Ace pops out on the flop, and it's bet into me, I'm out of there. If it's checked to me, I'll put out a feeler, but I'm gone to a raise.On the other hand, if a King or a Queen pops out, there's a much, much stronger possibility that the jacks are still good. I'd raise the flop (just once), call a single re-raise, and fold the turn unimproved.The other flops are those so-called good flops for jacks (for the most part) and should be straightforward.I'm not necessarily saying that this is the "textbook" and "correct" play, but it seems to match up pretty well with the kinds of hands that you'll see most of the .25/.50 opposition playing.