Learning the rules is important and the above suggestions are great. I would suggest you do not purely focus on the rules, but study mechanics. When watching games on TV or video, in addition to looking at the plays, watch where the official in your position moves and focuses his attention. As was said, unless you are in Texas, don't pay much attention to the NCAA rules as you will be as confused as the high school fans at your games, but the mechanics are generally the same.
If you are free on a Friday night, but do not have a crew you can follow, go to a HS game and watch from the stands (better view)how the officials position and move. Rules are important, but if you are out of position or focused in the wrong area, they do not help much.
Also, I agree Rule 2 is extremely important in understanding the rules. Memorize the definitions and all the rest will be much easier to understand.