Over the course of an offensive play, take note of exactly what happens. If the team passed, track who threw the ball, who it was thrown to, whether or not it was caught, how many yards were gained, and if they scored a touchdown. For a running play, track who ran, how many yards he gained, and if he scored. Also be sure to take note of any turnovers, including who fumbled the ball or who threw the interception. By tracking these foundation stats (the specific events that happen on each play), it allows you to make calculations for more in-depth stats, such as completion percentage, passer rating, average yards per attempt and more.
During the same offensive play, also keep track of what happens at the end of it, including who tackled the ball carrier or assisted on the tackle, broke up a passing play, intercepted a ball, forced and recovered a fumble, sacked the quarterback, etc. A tackle is defined as when a player tackles an opposing player on their own, while an assist is given to any player who tackles an opposing player with the direct help of a teammate. Sacks are awarded in either single or one-half increments, depending on whether the player sacked the quarterback by himself or with the help of a teammate. Similar to offensive stats, tracking these basic stats allows you to calculate in-depth defensive stats in between plays.
Kickoff or Punt
During a kickoff, identify who is kicking the ball, then track how far the kick traveled, in addition to the player who tackled the ball carrier, and where the ball ended up (average opponent start). For a punt, keep track of the punter, how far the ball traveled, the player who tackled the ball carrier, how long the return was, and if the play finished inside the opponent's 20-yard line. These stats will allow you to figure out net kicking averages (the difference between the kick or punt and the return). When tracking a kick or punt returner, after identifying who is handling the ball, track how many yards they ran, and if they scored a touchdown. Again, the stats will allow you to calculate their average return for each situation.
Field Goal or Extra Point Attempt
During a field goal or extra-point attempt, identify who is kicking the ball and track how many attempts were made and how many were successful. Field goals also can be broken down by distance to the goal posts. Be sure to also track the defensive side of the play, such as if a player blocked a field goal or extra point, in addition to if they scored on the play. Keeping the basic field goal and extra point attempts allows you to calculate the success rate for each scenario.