A great article over at T-Nation on how to improve your bench press.

• He gets his entire body super tight to create a stable platform.
• He uses his lats to pull the bar out of the rack to make sure his shoulders are in good position.
• He pushes his belly up and drives his shoulders into the bench and imagines that he’s moving his body to the bar.
• As he tucks his elbows and lowers the weight, he tries to bend the bar and pull it apart.
• He keeps a tight arch and his back tight the entire set.
• His triceps are thick and strong, allowing for a strong, smooth, lockout.
• His upper back and lats are thick, allowing for a more stable press.
• He uses leg drive to start the lift after the press call and keeps his glutes tight throughout the set.

Go read the article for full details as well as useful videos to help explain the concepts.