Players typically pick very poor spots to push all in. In my experience, it is a very bad idea to push all-in in any early position unless you have a killer hand such as AA, KK, QQ, JJ, AK, AQ. I will often fold pocket 8s and below under the gun (1st position after the blinds). The reasoning for this is that in a full ring game you have 8 other player to act after you. If any of them have the chips to spare and have even a marginal hand they may be willing to call you.

Playing short stack poker is all about getting a double up, not stealing the blinds. The best way to double up, of course, is to have the best hand. A major part of this is to make sure you do not call raises or re-raise all-in. Unless you have aces or kings, you do not want to be playing against another player that is telling you that they have a strong hand. If you call another player's raise, you really have no idea if your hand is best or not and are taking a big chance by calling. You could easily be dominated or be up against a hand better than yours. This is a common mistake of beginner players.

What you want to do is move all-in with the best hand and be called by the second best hand. This is known as "first-in" strategy. You want to open the pot when a number of players have already folded and you are the first in (in late position, another critically important concept). This increases your chances of winning based on the fact that there are less players to call you and the fact that you have put the decision to them, rather than them raising and putting the decision to you.

A.Cooper