There are many different circumstances you can find yourself in during the course of a football game, so you won’t be able to prepare for them all. That being said, there are some areas that you can expect regularly, like third downs, short yardage, or the red zone. Have a clear idea of what you want to do in these circumstances, and practice them regularly so you can be confident when those moments arise.
With 22 different people running around on each play, plus many coaches shouting instructions, there is a lot of information. Make sure you are clear on what you are supposed to be doing in any given situation. Focusing on your role and your actions will allow you to remain calm and perform them to the best of your abilities.
Watch film and read reports about what your opponents like to do. Scout in person if you can. You’ll want to highlight the other team’s key players and favorite plays so you can think of ways to neutralize them.
Just like you are watching the other team, they are scouting you, and unless you are far more talented than your opponents, you won’t be able to get away without something unpredictable. Look for different formations or shifts you can run, and study your patterns to vary plays and techniques. Anything unexpected for your opponents makes it more likely to get a big play.
Find distractions before and after the game. You will spend plenty of time in practice getting ready for your opponent and finding ways to win. Make sure you take some time before and after the actual game to do something else to distract you from the moment, and give your mind a rest. This will help you relax, and can make your focus during the game that much better.