This is so much easier in today's world than just a decade or so ago. No matter what you're doing, working on a wreath, a fireplace, display or the tree, take a digital picture or two during the process. It's amazing how much different it can look in a picture, than just viewing with the naked eye. Even though you think you can see it all, the camera will show where those empty spots are, where a little more garland is needed or even when too much is just, well too much.
An excellent example is when I thought I was just about done with a tree yesterday. I took a quick picture and after looking at it I see too many bare spots, and one area where ornaments need to be spaced a little better. Back to work!
I probably am over the top when it comes to things like that, but if you think I'm bad, you should see some of my friends.