It depends on the chip situation at the table. If you're the short stack, then you have to double up or at least chip up enough so that you're not the short stack. If you bust out in the process, well so be it.
If you're in 3rd, and the 4th place player is close to your chip count, then you still are in danger. You need to be a little more cautious because you do have more equity in this spot, but that shorty could easily overtake you, leaving you as the short stack, in which case you revert to the previous ideas.
If you're in the 3rd and the shortstack is very short or crippled, you have to be SUPER tight. If he's short enough, I'm talking folding KK and maybe AA preflop tight, again depending on how the chips are distributed. But you have so much equity from letting the shortstack die, that you simply cannot for any reason put that in jeopardy.
If you're in 2nd place, you have to be tightest of all. You have a TON of equity now, and are virtually guarenteed to make the money. If you get caught up in a hand you shouldn't have and get crippled by a shorty who still had enough of a stack, or you make the awesome play of going against the chip leader and lose, then you just forfeited so much money that I'm going to puke. So you have to be the tightest in this spot.
As the chip leader you have free will to basically own the table. Especially if you're a significant leader. If the other players understand bubble strategy, (they probably don't) then they simply have to fold almost their entire range, and for some people, like the 2nd place guy, his entire range. You have the threat of elimination, and everyone who's not the shortstack is going to run away, expecting the two of you to get it in eventually. You'll often pick up so many chips before that hand comes around that it ends up being a freeroll. And if the two shortstacks are near one another in chips, it's even better. They both fold trying to outlast the other one, and you just rob them blind.