I have an entire 6 foot bookshelf full of paper. It is sorted by size, kind ( vellum, patterned, foils, handmade, basic cardstock, etc.) This is for full size sheets. My " scraps" are stored in pizza boxes labeled by color. On my work table is an old cheese box that holds smaller " scraps". This way if I need a small piece of a certain color - such as a scrap of yellow to make a sun - it is right at my fingertips, and I don't cut up a full sheet.

one of the best way is to keep it in scrap box

I love the sound of sandy's studio! I would simply adore having the space for shelving.
Right now I am set-up in our living room behind the flow of traffic and living area. I'm grateful for this space because I do have storage as well as a great work table and relaxing chair on wheels. I store my full sheets of paper, both 8x8 and 12x12 in a wonderful file box made just for this purpose. I store my scraps in a very inspiring art deco box I bought at a craft store. I know though that I will soon grow up and out of this solution as my stash seems to continually grow. I simply love any kind of paper.
Good thing we are one in the minority now and are looking to buy a new home!
I'll be able to use Sandy's tip. Thanks!