For activities beyond the game itself:

*Get reservations to swim in the midway crater (sooner rather than later, they book up quickly)
*Do this in tandem with a drive up Provo Canyon and a stop at Bridal veil falls. I always took that place for granted growing up in Utah but its one of the most beautiful stretches of road in the state.
*If the BYU store is not open, the store in the stadium will be so just plan on arriving early more on this below.
*Traffic is about as bad as its ever been for BYU games, Park in Orem and catch the bus if you can but get there early.
*Depending on gametime a visit to Chubbys is absolutely a must pre or post game. 2nd best burger in all of Utah but number 1 overall experience. (burger supreme a clear #1 stand alone burger. Dont come at me).

*Enjoy the game. Again, get there early. Im seriously amazed at how getting in and out of the stadium keeps getting worse and worse.