Add eight teams (one per division). There is so much demand for professional football, and I would love to see more teams. Portland, San Diego, Mobile/Birmingham, San Antonio, Albuquerque, Richmond, St. Louis, Salt Lake City. It would also be awesome to have international teams, though it probably couldn’t work logistically. But some cities that would be candidates: México City, Vancouver, Montreal, London, Paris, Munich, Amsterdam, Madrid.
Eight teams make the playoffs from each conference.
Increase schedule to 18 games.
All of the sports leagues want longer schedules and expanded playoffs but are unwilling to create more pieces of the pie. First league that undergoes mass expansion will become wildly popular. The 30-team league is a concept from the late 60s/early 70s. 40 years later times have changed.