I would recommend these:
1) Agility drills.
2) Speed ladder.
3) Short distance sprints.
4) Playing as much as possible.
Players think that if they are "slow" there is nothing they can do about it. That is not true. You can improve your speed, quickness, and reaction time if you train. You have to improve the physical side of your game and you can and I'd love to help you.
Thanks! and by the way, I've seen your youtube tutorials before and they're great!
So I play rec soccer and its only our 2nd practice. After running, we did a drill with passing and shooting. When I passed the ball,coach yelled at me because I waited for about 1-2 seconds before moving because I forgot what we do next. How can I think faster and make sure that I don't mess up again?