basically what eheath said, there are going to be times and shots that you won't necessarily be able to look at the viewfinder/monitor for framing and you'll just have to trust your cam. Either be focusing your vision directly on the talent, or on the viewfinder with the talent in the background (second method is a little sketchier as you have to be aware of other things/people that might be in your way) but I have found that whenever possible, I try and frame the shot from the viewfinder rather than looking at the talent and 'guessing' where to aim the camera. That said, the more you practice, the better you'll get at shooting without looking at the framing in camera.
Shameless self promotion, but this I remembered trying to frame in camera, although there were plenty of times that I simply had to take my eye off the camera and guess where the rider is. Shot with glidecam 2000hd / tokina 11-16