How about increasing tries to 6 and making conversions 1 like NFL.
Copying from the NFL again bring in the 2 point conversion play.
From wikipedia changing it to rugby:-
In rugby union, a two-point conversion is a play a team attempts instead of kicking a one-point conversion immediately after it scores a try. In a two-point conversion attempt, the team that just scored must run a scrum or lineout from close to the opponent's goal line (5metre line) and advance the ball across the try line in the same manner as if they were scoring a try. If the team succeeds, it earns two additional points on top of the six points for the try. If the team fails, no additional points are scored. In either case, the team proceeds to a kick off.
Here's another idea. How about removing the current 2 yellow=1 red situation. Only make the red card applicable for very serious offences. Two professional foul's shouldn't be a red imo.
I think that it it would lead to players not being as afraid to infringe but it would also mean refs wouldn't be afraid to yellow card as often. Meaning an increase in yellow cards and more space on the field.
Maybe we should even have third different card. One for dangerous play that isn't punishable by red card. Two of these would lead to a red card.