My guess is that what you need is more description, not more rules. (sorry Nathal)
However, I agree with Eric that a more challenging environment might help as well.
A goal for me when my game returns from hiatus is to be descriptive as the GM in combat. I think I'm generally pretty good about keeping things from being more like:
"The minotaur brings his axe in a huge sweeping arc and brings it squarely down on Karrinkas' hind-quarters, smashing Karrinkas off of his feet. (oh, and Eric, that's 60 points of damage)."
instead of:
"The minotaur hits, possible critical with a great axe! It's a critical! That's 8+10+6+36 = 60 points of damage. I guess Karrinkas isn't uninjured anymore!"
Some players pick up on this, at least in my group. Be warned that once you become more descriptive, you'll have players who say things like:
"I step in over Karrinkas' unconscious body, raising his axes in a defensive stance. I want to make sure I've left room for Arlissa to get a hand in there to touch him with a healing spell. I rolled a 17 and a 14 with the penalty for Full Defense, did that 17 get in?"
Which means you get to adjudicate how much cover a brave comrade gives to a prone and unconscious friend, and whether them standing there will prevent the attack of opportunity on someone trying to deliver the life saving spell.
Now for my money, I enjoy that a lot more, but you have to be ready for the players to get descriptive as well.
John