From: http://www.soccer-training-guide.com/be-a-better-soccer-player.html#.Xjmy2GhKiUk

Running for 3-4 Miles With Hill Runs

Conditioning is one of the most important things that you need to learn. If you aren't fit, you're not going to survive your first soccer game.

Learn How to Play Soccer With Both Feet

That's what's going to get you noticed by coaches, scouts, and other people that can turn your dream of playing soccer professionally into a reality.

Switching feet strengthens your body so you have as few weak points as possible. You want to be consistent with this - results won't come overnight.

Learn New Things Every Day

Spend at least 30 minutes on learning new soccer skills every day. 

Watch Pro Games

Try to watch professional soccer games often. This may sound pretty obvious but believe me you would be amazed if you realize how few players are actually doing this.

One thing you should keep in mind while watching pro games is to pick a player who actually plays on the same positions as you.

Bring a notebook and write down what he is doing when receiving the ball.