NOTE: Updated as of August 2019.
Artist grade paint:
Cadmium yellow light
Transparent oxide red (or a dark burnt sienna)
Alizarin crimson (or permanent alizarin crimson)
5-6 natural bristle (square shape) brushes of varying size (approx. 3/16" up to 5/8”)
1-3 round bristle brushes various sizes (can be nice)
3-4 sable or synthetic "softer" brushes various sizes and shapes
Make sure you have a variety of sizes of all brushes
Palette: (middle tone)
Brush cleaner: Either metal or "Silicoil" type.
Gamsol or Turpenoid (one of these two only). Do not use "Turpenoid natural"
Mediums: Fast dry mediums are either Gamblin Galkyd lite, Neo-Megilp or Winsor & Newton Liquin. Or just linseed or walnut oil (artist grade)
(My preferred medium is 1 part linseed (or walnut) oil to 4 parts Gamsol.) If you choose this, bring a container for it
Support(s): Any of these sizes or a variety of 8x10, 11x14, 12x16 or 14x18 canvas or panels, 5 or more total (be safe make it more).
Paper towels, palette cup, palette knife(s) etc
Wet painting carrier can be a good thing
Sketch pad with assorted soft charcoal or graphite pencils, kneaded eraser.