At risk of being redundant, I made up a very serviceable and inexpensive travel paint kit from an Altoids tin, using silicone caulk (the kind that is sticky and hardens) to divide the bottom into eight sections, into which I put my most-used Winsor Newton tube colors:

Quinacridone gold
Cadmium yellow medium
Cadmium red light
Quinacridone magenta
Ultramarine violet
Ultramarine blue
Winsor green
Sap Green (I like the Talens brand too)

I painted the inside of the lid  with white enamel paint and use it as a palette.

The only other things in the the bag are a kneaded eraser, Pigma micron pen, a mechanical .3 pencil and two Nidji waterbrushes - large and medium. Oh, and a sponge to wipe the brushes on. : )

My 'studio' has been my kitchen table for years, until I found a great little drawing table - ostensibly for kids - that can be raised and lowered to any height, stained a dark walnut color to blend in with my other furniture. I have a small stool on which I put my butcher's tray and a wooden storage box from IKEA for the paints and brush roll and things, that usually live underneath the drawing table until I can pull them out to work. It's a good size. My one big splurge was a standing Ott-lamp that has a color-balanced bulb, so I can work into the wee small hours should I want to. : )

Kathy