One of the things I have always done for each media I ever worked with, is making a colour chart.
It is a lengthy process when done properly but it is soooooo worth it! Firstly it greatly helps getting a "feel" of what the medium is like, how different colours work with others, how strong the pigmentation is, etc. As I have recently started working with oils, it was time to spend a weekend making charts :)
I divided A4 sheets of Arches paper for oils in a selection of squar