[J.A.Sucker]

I'd call with QJo in loose, passive games like you describe at first. In LP, I'd consider raising, but would be more inclined to limp. In both of situations, I think you could raise if you think that most of the remaining players behind you will fold. This may be the case, if you are seen as a player who plays tight preflop.

In tight games, I would either fold (majority of the time), but in a very tight game, I would raise first in (sometimes) to try to steal the blinds. This can be done UTG in some games, and is worth a shot, IMO, when everybody is very tight. If you get called or 3 bet, then you have to play very defensively, but I think that in these games, KQo and AJo will usually be folded by players behind you, and the chances of being dominated are small, so it's not so bad.

These are just my ideas, but I'm Just Another Sucker.