Use a color scheme when organizing your paper.
Quick tip, long explanation!
Use ROY G BIV or some other color system best known to yourself when you organize your paper. This works extremely well for plain card stock, but can also work very well for patterns if you do a looser version.
For those of you who do not recognise ROY G BIV, it is an acronym for the colors of the rainbow. Red, orange, yellow, green, blue, indigo, and violet. I put my papers in this order in Cropper Hopper Vertical paper holders. I put the creamy-not-quite-yellows with the whites and off-whites, and browns in the front. And I put blacks and greys together in the back. I made pinks a shade of red so they are in front, behind the creams and in front of the reds.
I arrange the papers light to dark, front to back.
I arrange my cardstocks together and then the patterns are together in a different paper holder, or I guess I should admit paper holderS!
Pattern papers that have several different colors, I usethe dominant color that popped out at me to arrange them in ROY G BIV style within the themes. If there isn't really a dominant color, then it goes into the front where I have an array of multicolor papers.
Any of my papers that are specific to a certain theme go into my pizza box for that theme. For more information on my pizza box storage see the article listed below called Organizing Stickers and Diecuts.
The last tip I will add from my paper storage experience is that I also have one paper holder specifically for collections. All of my collections of paper that coordinate together stay in that paper holder. These aren't specific in color but I can easily grab what goes together by storing my collections this way.
I hope this helps you a little bit, no matter where you store your paper. Hopefully it will make it a little easier to find and use what you have already, so you don't go out and buy something, just to find that you already had that in your pile!