I don't think there is a guaranteed way to get invited into a better conference. I got invited into the WAC after my first season and declined and since then I have had 3 undefeated seasons, being ranked as high as number 2 in the final polls with heisman winners and many all americans, having top ten recruiting classes and getting North Texas up to a 6 star program. After 4 total seasons and having only lost 1 game which was to LSU in the first season, the WAC invite has been the only one I have gotten, but at the same time I'm sure there are other people who have gotten an invite into a better conference than the WAC in less time so I don't think there is an exact way of getting into a better conference. Just keep scheduling top 25 teams for your non-conference games and win every game, thats all you can really do.