Here are a list of variables that you can tinker with to become a great tactician
Surprise - Can you add an element of surprise that will reap rewards before the opposition get time to counteract, or will the surprise force the opposition to change their gameplan.
Speed - Applying greater speed ( Running / kicking/ general execution) to your game than your team are renowned for can catch the opposition napping.
Numerical Advantages - With teams playing men back, there are lots of opportunities to create 2v1 and 3v1 situations in certain areas of the pitch. Same applies in defence.
Pace of the Game - If you are playing a team that likes to play at a fast tempo, why not slow the game right down, or vice versa.
Exploitation - Every team and every player has at least 1 weakness, find it and exploit it, It's not always what it seems. Train your eye to spot these weaknesses.
Match Ups - Get these right and everything else is so much easier. Your opposition will be trying to get these right too. Use this to your advantage also.
Psychological Tactics - What mind games can you play to psyche out your opponents, but be careful, this can just as easily backfire, especially in the longterm.
Time Management Tactics - Manage the game by performing differently at different times in the game, 1st 10mins, last 5 minutes etc
Black Art Tactics - Time wasting, Fouling.... etc