I'll get right down to the basics. Pre-flop starting hand requirements go out the window in short-handed games because short-handed No-Limit Hold'em (SHNL) poker is all about the set.
The Mystery of the Set
It took me two years of playing to realize how powerful the set is in SHNL. Sets (aka three-of-a-kind) are very mysterious because they're almost impossible to pick up and even harder to hit. You'll hit a set on the flop about once every eight times you play pairs.
The reason we play sets, or a "money hand," is because most opponents won't put you on three-of-a-kind when you bet. Pairs must become your best friend at a short-handed cash table because they can be devastating in SHNL.
Sets Win Big Pots
Forget about aces. Forget about kings. Sets make the most money in SHNL. When you hit your set you'll almost always rake in a decent pot. Think about it: when you have aces and lose, the most common hands that beat you are sets and the occasional drawing hands. That's why I always call a raise (providing it's not too huge) with any pair - when I hit my set, I get all-in action at least half the time from those players.
Let's say you call a pre-flop raise of $30, and you and an opponent are sitting at a table with $600 each. True, most of the time you'll miss your set, but when you hit, you have the opportunity to take his entire stack.
SHNL is all about implied odds, not pot odds. If you're drawing expensively, but your opponent is sitting with a lot of money, it would be correct to draw. The same goes with a set. Learn to play pairs and you'll become an artist at short-handed cash games.
Pairs Are Easy to Fold
When you miss your set, pairs are the easiest hands to fold because you're in no way committed to the flop. If you miss, you fold. If you hit, you're golden. It's as simple as that.
How to Play Sets
Always bet your sets on the flop. I make the most money when I bet and get my opponent pot-committed. If you know your opponent will bet, then by all means check to him, but I'm strongly opposed to slow-playing any hand and advise against it.