"are you modeling with the Camera set to Parallel Projection?"
Yes. Isn't that the best method?
"I read it and it reads as if you not pressed F1 and read the docs on using SketchUp."
You are right! Sorry!
"Are you just moving around in model space or maybe changing from perspective view to parallel projection view and back again ???"
I just try to move the object to that one I want to snap to and turn around to approach it; I don't change the projection in the camera menu.
Ok, what Rich wrote seems to be the answer to my question.
Thank you