The "Pain in the Net" Tactic is where there's a player in front of you, and a team mate at the side of the player, then you pass to him (you play a sort of mini 1-2, by passing to him, then running round the opposing player, then your team mate should pass back to you (this tactic should be played near the goal), then you control it and do a power drive at the ball, and it should go in! (This tactic is best used with a player like Milan Baros or Thierry Henry)
Variations of the Pain in the Net Tactic include:
The One Two Three Four Tactic
The Nutmeg Powder Tactic
and
The Worth a Trip near the Goal Tactic.
Try it in Training Mode to practice it. You'll soon get it!