I recently completed some colour charts. I have the book Alla Prima by Richard Schmid. He suggests doing them to learn exactly what effect colours have on each other including adding white. It was very revealing. I lean towards the earth tones. The colours I used are Cad Yellow Light, Cad Yellow Middle, Yellow Ocher, Cad Red Medium, Alizarin Crimson, Cobalt blue, Ultramarine Blue, Raw umber, Raw Sienna, Venitian Red and Black. The first chart is all those colours with levels of white added. Each square is about 3/4 of an inch.
The Alla Prima book is the best "how to" painting book I've encountered. A must read. Practical knowledge in an informal presentation. Not to mention beautiful work.
The process took about a 3-4 days; two to three hours each day. I painted on Arches Oil paper. The paper presented an easy surface to manipulate. I plan on spray sealing the each page and then put them in a book/binder/holder to use in the field or in the studio.
A blog about active art projects and En Plein Air adventures among other art related musings may be mixed in.