run more.
But honestly, I'd just work on agility and interval work. Soccer isn't an endurance sport (eg long periods of constant movement), so working on short cycle sprint work and agility is probably going to pay off the most.
The best thing you can do is to play around with movement in different planes. Twisting, quick turns, suicide sprints, etc. People get really easily injured in field sports because you have to change direction so quickly while moving your body in ways that it doesn't like.