This is a common question. First and foremost you want to keep things simple so your brain can follow along and find your stuff. Where shapes are concerned, my recommendation is to simply add a section to your 4 Section System and call it "Shapes."
This is a great place to put everything from arrows to tags, circles and squares.
Include representations of punches, dies, and even rubbings of embossing folders.
There is only one shape that I don't have in my "Shapes" section, hearts. I think of hearts as Valentine's Day, so everything I have that is a heart is in February.
Hope this helps. Thanks for stopping by today.