> Keep two water reservoirs for cleaning your brushes. One for warm colors and one for cool. (This prevents muddiness in your palette).

I used to do a cup of designated dirty water and a cup of clean water but I can't think on that level when I'm painting. I'm close enough to a sink that I just change it out as needed. Any cup near me when I'm painting is going to get all manner of brushes dunked in it. Yes, I've dunked a paint-loaded brush in my coffee before.

> Knowing when to let the layers on your paper dry before further progress is vital.

Only slightly less vital: knowing when not to let the layers on your paper dry before progressing. But yeah, that one first.