1) No tackle football before a certain age (to be determined by scientists based on brain development and how damaging a concussion would be). You can learn a ton about football, running routes, learning plays, getting in shape, etc. without hitting people.
2) Ban hitting. Everything should be a wrap around tackle. No more players running full speed and launching themselves into other players. Look at how few players actually try to tackle people.
3). Put padding on the outside of helmets and maybe shoulder pads. Current helmets are not doing nearly a good enough job of slowing down energy. They are designed to protect against fractures, but future football equipment should be designed to slow down impacts.
4) Make neutral zone a few yards long. Much of the worst blows happen to linemen who fire off into each other, particularly on running plays. While big hits get the most notice, it is actually those who are suffering routine head blows that are at the most risk.
5) Ban the quarterback sneak and any other similar play where linemen dive into each other in short yardage situations.
6) Ban players for unsafe hits. 15-yard penalties are not nearly enough for something that could cause someone to die very young.
7) Ban players for PEDs. Steroids and HGH permanently alter your physiology. PEDs are making players unnaturally big, strong and fast. Suspensions are not enough, because even if a player stops doing them, he may have made himself unnaturally big, strong and fast.
8) Allow defensive backs to hand check and other ways of playing defense that don't revolve around big hits. The passing game has exploded in the NFL, partly because it's so hard to defend against receivers. Receivers get more separation these days. Allowing hand checking closes separation and would limit the amount of passing.