Most beginning artists will quickly realize that in
order to work efficiently and effectively, one must
develop a good physical system for one's materials.
Grouping one's colors is an obvious way to work.
Here is a shot of a friend's colored pencils. Paint
tubes can be stored by colors in separate containers
which is what I do. Pastels present a unique challenge
because of their 'dusty' nature. I always have kept
mine in order in the box I have which has something
like 72 colors in it.
The goal is to be able to locate visually what you want
If you have your materials all over the place while working
which I often do, be sure to discipline yourself to put them
all back where they can be easily found for the next time.