Practice. Good football teams are successful because they do all the little things right. It’s at practice where good teams work on these little things. Practice is the only way one can develop a hands-on familiarity with how to execute a new blocking technique or see how much more explosiveness changing your stance can give you. Practice is a time to run drills and work on plays to better equip you for game time. Essentially it allows time for the kinks to get worked out and to see what works, and what doesn’t.
Study your opponent and your own team. Does your next opponent have a star receiver? Is their defense susceptible to giving up big running plays? If so, that knowledge would be useful before the opening kickoff. With some sort of pre-game planning, you can figure out how to shut that receiver down or develop an effective blocking scheme to further augment your opponent’s problems with the run. You can work on your new strategies in practice (see step 1). But it’s also important to know where your own weaknesses lie. For example, if your own team has difficulty covering punts, maybe it would be a good idea to have your kicker work on aiming the ball out of bounds. Or, if your left offensive lineman is injured and has limited mobility, maybe it would be useful to back him up with your fullback.
Train. Football is a game of speed and strength. The better physical shape one can get in by game time, the better. Given that football requires a lot of running around, it would be useful to have a good cardiovascular base. It’s human nature to get lazy when we get tired. In football, that laziness can translate into a missed block and a loss of yardage.