I think first and foremost the quality of games needs to improve for a substantial increase in crowds to come about. The entertainment factor is why IMO the majority of us were initially hooked to the game, and is the primary factor in creating a new generation of fans.
A few suggestions to improve would be (for a sustained increase in quality)
- Investing in coaching development at all levels, academies etc
- a small technical committee headed by a technical director to oversee trends in the comp (akin to the FIFA one)
- overhaul of the refereeing/rules management
- a national over aged reserve comp
- Introducing new and specialised training programs to juniors devised perhaps by a technical committee to promote skillful, free flowing, inter-linking attacking play whilst also keeping a strong emphasis on defence
To me it's the only thing that will drive a big increase, anything else will merely be putting lipstick on a pig.