There are several different rule systems you can go by to set your game up with, or adapt your own set. Part of the answer depends on how complex you want your game —is it just a fun lark, or are you out for a full-tilt real-as-can-get simulation?
The simplest method would be to just play both sides by the Tudor rules. If what you want is to have fun with some fast games,
Brian McAtee has a set which seems to work well enough for him and has led to hours of enjoyment with his Imaginary Football Land. And at the other end of the spectrum is
Anthony Burgess and his Miniature Professional Football system, which would be an MF analogue to
kriegspeil as a detailed game attempting to model real world conditions as much as possible on its scale.
The main challenge is to stick by the rules and allow the game to unfold as it will without favouring one team over another and attempting to "fix" the game for that team. Impossible as it seems, it is not unusual to end up pulling for one team out of the several in your league, as I've found playing my tabletop baseball leagues. I strictly adhere to the rules which define my games, and the verdict of the dice is always final.
Try playing out a few game with the Tudor rules, if you've got that set, or visit any of the EF league websites and adapt their rules to your game, and see what suits your temperament.