I'm not sure exactly what my sliders are at, but I know I didn't move false start too much, and I don't really have much of a problem.
In real football, false start happens about as often, or perhaps slightly more often than offsides/encroachment. However you set your sliders, they should reflect this.
If you play 8 minute quarters and are averaging 3 offsides/encroachment per game, then you should average 3-4 false starts per game.