Positioning. You need to know where you are on the field at all times, and how to put yourself in the best possible position to be a threat to your opponent. The easiest way to get this down is to watch a professional team who plays the same formation as your team, or a player that plays your position. Watching them will allow you to see the best way to position yourself, just as the professionals do. This will keep you in a better position to succeed on the pitch, whether its being in the right spot to score the winning goal or make the tackle on the game, this will make you a much better player.