Instructions
Analyze your current chess strategies. Do you tend to think carefully about each move? Do you think three or four moves ahead? Locate a few problem areas in your game strategy and write them down.
Come up with a general game strategy before you start playing. One reason why most people can't play aggressive chess is that they don't have any plan when they come to the table. If you have a plan, you can think about how to adjust it in the midst of the game. Without one, you will give your opponent too much time.
Play with speed. Having a plan allows you to come out with definite speed and throw your opponent into a panic. Your opponent will simply react to your every move quickly without thinking. After several moves, you will have him on the defensive and sacrificing pieces to stay alive.
Attack specific pieces quickly. There are a few pieces that are far more expendable than others. You should be willing to sacrifice pawns and bishops before rooks and knights (although this could vary with your strategy). Eliminate rooks and knights quickly so that your opponent has to use her queen.
Play some mock games with a friend using a clock. See what sorts of counter strategies they come up in response to yours. Write down possible moves to alter your strategy given the moves of your opponent. Try to keep moves to 30 seconds or less.