I tend to use the RWBY method, myself. For blues/greens/greys, I use an OC named Azura, and for bed linens, I use Zwei... because sleeping involves Zzzz's.
In case you've never watched RWBY, the four main characters -- Ruby, Weiss, Blake, and Yang -- are represented by different colors -- Red, White, Black, and Yellow, respectively -- and I use this to help me separate my laundry. It's weird, I know.