This is how I keep my 8 1/2 x 11 Stampin' Up! Cardstock organized. I bought this paper rack from a local craft store that was going out of business. I've had it for over 10 years and I love it... I like that it's compact and stores my cardstock vertically. I stack the cardstock according to the Stampin' Up! color families. You can see the little strips I have with the colors and names. I created the strips in MDS and laminated.
I know that most crafters are challenged on how to store their paper scraps. I like to put my scraps in a hanging pendaflex file. I have a hanging file for each color and I just put the scraps in their folder. It makes it easy to check for scraps when I need a particular color. I do not keep the really small pieces, it's not worth it because they get damaged and wrinkled. I also put these in the color families in the same order. I bought this crate at Staples.
I like to have White cardstock as my first file since I use so much white for my cards and projects.