I know when I started Squatting heavy my (weekend hack) game improved a lot.
I'd say look into working with a
'power' routine (low reps heavy weight) to build the most strength you can in your key areas, rather than a high-rep hypotrophy routine (which may or may not gain you size but will almost dfefinately not net you max
strength gains).
As Justice said you already know what is required to play soccer (i.e. what muscles control what movements) and where your weak points are. Pick exercises addressing those areas you want to improve and have at it.