longhornn04 wrote:on middle pairs i like to limp in or just go all in
That's a pretty general statement. You should play middle pairs differently based on your chip count, the chip count of your opponents, and your position at the table.
If I'm in early position, I'll usually limp with middle pairs. If I'm on the button, or one of the blinds, I may occasionally raise. Of course that all depends on how many players are in the hand before me, and whether or not they've raised the action to me.
I agree with Phil Gordon about just limping with small or middle pairs. You're accomplishing a few things by doing this. One, you're not risking any more chips than necessary to see a flop. Two, with a small investment, it's much easier for you to get away from the hand if you miss flopping a set. And three, by just limping pre-flop, you're disguising your hand. If for example you had 9's and just limped, and the flop came down 9 K A, you have the potential to win a much bigger pot than if you'd raised before the flop. If you raised pre-flop instead, your opponents become much more cautious, especially if the flop didn't help them.
Let's say in this same example, you raised pre-flop with 9's, and was just called by an opponent with A 10 or A J. The same flop came down (9 A K). Because you raised pre-flop, this opponent may feel you have A Q or A K, and therefore feels like a big underdog in the hand. When you bet at the pot either on the turn or river (if you decided to check the set), he or she is much more likely to fold the hand than if you'd limped with the 9's pre-flop. This opponent would probably feel much stronger about their hand, and you'd get the action and opportunity to take down a bigger pot because of it.