There's loads of stuff you can do to improve speed, and i think what you mean here is improving your acceleration.
I would say look online for things relating to SAQs (speed, agility and quickness exercises) and that will get you started. Building up leg muscles and the like.
Otherwise, you can do lots of short lengths of sprints, 5,8,10m to try and speed up. It can be annoying to start because you feel like you're only beginning to get speed then it's all over.
Maybe try things like starting facing backwards, starting on knees, starting lying down which are probably more reflective of a game.
Not a great reply, but somewhere to get started anyway.