The tracking technique
that works for me is just to use both eyes at the same time - your
right eye looking through the viewfinder, and your left eye
straight at the subject. Find the distant subject with your left
eye, and point the camera at it. While you are doing this, keep the
images that your left and right eyes see distinct - don't let your
brain choose just one image. You'll see a superposition of images -
the direct visual image and the viewfinder image. Move the camera
so that the direct visual image of the subject is superposed within
the focusing brackets in the viewfinder. For distant subjects, this
means that the camera will see the subject within the brackets as
well.
The technique is easier to do than describe, but with a little
practice it works.
Hanscom AFB air show, June 1 -2. Taken from a parking lot a mile
from the base, so few real close-ups. But the technique of globally
tracking with the left eye while framing in the viewfinder with the
right was indispensable here.