Eliminate the clock stoppage after 1st down - that will speed up the game, plus eliminate most of the confusion with the clock operators.
I can't believe how many times someone is near the out-of-bounds, just got a first down, we wind our arms twice, then stop the clock. The clock stops. The referee then winds his arms after blowing the play in, the clock does not start. This is after a pre-game conference on this exact thing. This is pretty much every game.
There are numerous other situations as well.
At least every 5 games or so, near the end of a game, like :10 left, the clock is stopped after a running play in bounds, and the losing team is out of time-outs - the winning coach is going ballistic about 'Why is the clock stopped?'. 'Coach - your opponent got a first down. We will restart on the ready for play'.
I know there might be some people who like this - to get the chains reset, but this really does cause more harm than good. I like the NFL way over the NCAA way - adds more excitement to the end of the game.