Yup, I sort by color also. My first year or two I just put them in a small clear shoe box but it did not take long to discover that I liked to feature a single color, or perhaps emphasize with a color in my quilts. I them began to put like colors into zip-lock bags by color. About 5 years ago, I just gave up and bought eight 13 X 9 plastic storage boxes at the Dollar Store. Yes, I have that many 2.5s. Generally there are two colors in each box. I keep one box for juvenile/i-spy/Christmas/Holiday because other than Christmas I don't have a lot of those prints. Another box is white/cream/black. Then as I sew/quilt and create scraps I cut the smallest pieces into 2.5 and put them in their color boxes. It works for me.
Reba, I have been entranced by 2.5's for a long time and admittedly it took awhile for me to discover my "style" for using them. If you want to sort, you can always start small, with zip lock bags perhaps. Even when making a true scrappy, it is often preferred to balance color intensity and it may be easier to do so when the scraps are sorted. Now after all my blathering, how your sort colors depends on you and the way you use color. I adore truly scrappy quilts that others make. Some quilters just dip their hand into a bag and add the color they pull out. I find this challenging and disconcerting. I guess, I like to control my scrappiness.
Good conversation starter!