Typical Indoor painting supply list:

D’ARCHES WATERCOLOR PAPER, 140 lb,  It MUST be Arches paper.  If you have any problem with this, let me know.  2 half sheets + some quarter sheets.  Bright White

Board that is bigger than your paper. Do not stretch, tape or staple your paper to the board.
 
    BRUSHES:

I like the white synthetics.  The brush companies keep changing their series numbers but look for:

1″ clear-handled Taklon flat brush — such as  Winsor Newton 995
#10 and/or#12 pointed round brush —white sable series 785 or Connoisseur series 367

Those two to start.  I paint 80-90% of my paintings with them. I also have a 4″ Skyflow and a #30  for working big areas.

And a tiny pointed one for signing my name!

LIDDED PALETTE — such as Aqua Pro, or John Pike, or Steve Quiller’s with

  artist grade  watercolor paint  such as Daniel Smith, Winsor Newton, Da Vinci, Holbein. Have at least 3 primary and 3 secondary hues.

Feel free to come with your own palette.

Be sure to have the basic 6 hues (red, orange, yellow, green, blue, violet)
If you are squeezing out more paint I suggest arranging your paints in a color wheel (ie rainbow).
I use Daniel Smith colors.
(cobalt green )
pthalo green, or Winsor green
(cobalt teal, cerulean blue)
pthalo blue, or Winsor blue
ultramarine blue
mypalettecobalt blue                 quinacridone purple (new)
(quinacridone violet)
quinacridone red or perylene red
quinacridone rose
cadmium red medium
quinacridone burnt orange (or sienna)
perinone orange
quinacridone gold
cadmium yellow light, or Hansa yellow light
green gold
+ any of your favorites

Update: I have added Quinacridone purple and taken out viridian; cobalt green is for sedimentary glazing.

All of the colors that are sedimentary are marked on the photo.  The rest are dyes or “stains” – no sediment.

a sketchbook
#2 or 2B pencils
white eraser
2 pint or quart sized water containers
a roll of tissue (tp)- a handy way to fix it is to take the core out of a roll and put it in a plastic container like a 24 oz yogurt container.  Pull the paper from the center… keep a wad in your non-painting hand for constantly adjusting the water on your brush.

on-line sources for materials suggested

merriartist
Friendly, personable; free shipping on orders over $90. Carries all of my art supplies including the W&N series 995 aquarelle

Daniel Smith 
the pigments I use. Check other values.

Jerry’s Artarama
Good source of brushes mentioned — type in Robert Simmons 785 watercolor

Dick Blick

Cheap Joe’s Art Stuff
often best price for paper