One thing you can do while watching your shot is to mirror it (check comments on how to do that in quicktime, thanks Rico!). You'll be surprised to see how much of a difference it makes.
Why do I post this? I was reading news on James Cameron's Avatar on Dark Horizons and it looks like he does the same trick to keep his eyes fresh:
I think something happens to filmmakers, which is that they watch their own action sequences so many times that they actually learn where the next image – where the subject coming in in the next image is. So they’re already looking there. But the audience doesn't do that. So, I actually watch all my action sequences bilaterally transposed. Flopped. When I get it all cut the way I think it’s supposed to work, I’ll watch it backwards. I don’t mean backwards in temporal order, I mean in a mirror, right? I’ll watch a movie in a mirror.
So my instinct to look where the next thing’s happening gets short-circuited. It’s actually – you realize how dependent you’ve become on your own watching process. But it goes back to that thing I was talking about before, which is – you’ve got to be able to watch your own stuff with fresh eyes, to anticipate the audience’s reaction. I think it’s an art, and I think it’s a discipline.
Of course why wouldn't he do the same, but it's always fun to know what pros are doing.