"a phenomenon of light".
Isn't that a wonderful way of putting it?
It made me want to close my eyes until I saw nothing, then open them slowly, jut letting little bits of light until they were opened normally. Then I wanted to again close my eyes until I saw nothing then quickly open them letting in the "phenomenon of light" full tilt. When I tried this I began to notice tints and shades. I began to focus on parts of areas in the room analyzing the colors together. Then imagining the colors as yarn crocheted to look like the textures of the things I was seeing.
Now you, go ahead, close your eyes (no peeking).
Now open them slowly, experience the "phenomenon of light". If you are having trouble seeing what this means, grab handfuls of assorted yarns, yes, I know you have lots of different colors. Place them in ramdomness (maybe toss them on a white sheet or towel) close your eyes and open them s-l-o-w-l-y. Do you see kinship in the colors and textures? Now put those yarns together and imagine them made up together. It might not happen then but from time to time do the above process again and it could hit you what to do with them.
Now on to "needs" to help in color combining.
One aid that is invaluable is the color wheel. There is a 5" size that is in arts and craft store that works great.
Sylvia Cosh did yarn carding. She did this to get different types of yarns and colors to make clothing with.
My suggestion is to do this type of thing with all your yarn. Take about a foot of it (yes you can spare it) and put it on an index card. Write on the card all the yarn information or tape the lable to the card. Don' forget to put how much you have of it. Do this with all your yarn. Carry it with you and you will have it to build up your color bounty as well as blending your colors and types.
Color can effect yardage. There can be less yardage in dark colors of yarn than light. I made this statement because it pertains to all you will do with yarn and your designs.