Someone requested that I post my studio palette setup, which is the same arrangement that I use whether I am inside, or outdoors on location. This is an open palette, even though I do not use all of these colors, I always put them out. My use of color is much more limited. I have always used this palette, and have a degree of comfort with it. I do occasionally introduce new colors, or experiment with a color that is not part of my tradional palette.
Mediums are another thing that I do experiment with somewhat, but always seem to return to the Ralph Mayer's formula of (one part stand oil, one part damar and five parts oderless mineral spirits). That is my go to medium if am in doubt, but I do like to shake it up every now and then by trying something different. Usually the result is not decernable from one to the other. It satisfies my urges to step outside of that comfort zone. The solvent or brush cleaner during my painting process is oderless mineral spirits ( Gamsol, or Turpenoid).
I use bristle and sable/mongoose brushes of all sizes. One has to experiment and play around with brushes to find what they are comfortable with, and what will make the statement they are intending to make. Some artists use only bristles to apply oil, and that is fine. I feel that for me personally, since introducing soft brushes some years ago, I found that contrary to some popular belief, one can doposite as much or possibly more paint with one of the sable/mongoose type brushes as they can with the Bristle brushes. Again this has to be a personal choice. No one can make that choice for someone else.
My palette is laid out from left to right as follows: Titanium White, Cad Yellow Pale, Cad Yellow or Cad Yellow medium, Cad Yellow Deep, Yellow Ochre, Raw Sienna, Cad Red, Permanent Alixarin Crimson, Terra Rosa and or Indian Red, Burnt Sienna, Cobalt Blue, Ultramarine Blue Deep, Cerulean Blue (optional or sometimes), Viridian, Paynes Grey.
This is the way I set things up for myself. It is not the only way, or necessarily the best way. There are many ways to achieve the same result. You might want to try it and possibly tweak it to suit yourself. Anyway, there it is and hopefully it with be of help, and useful to someone.