A couple of weeks ago I decided on a different approach. I limited myself to warm and cool colors, and decided that while I love pen and markers, the flexibility of colored pencils can't be beat. The idea for warm and cool colors came to me after being at the Stax Museum and not having a cool yellow with which to sketch a pair of Isaac Hayes' stacked boots that were a sort of yellow-green.
So I made a chart (of course): on the top are watercolors; then watercolor pencils; below that are my Dr. PH Marten's watercolor in brush pens - I can't seem to do without this yellow and this dark green-blue. On the bottom from left: mechanical pencil, Uni-ball Signo in white, Faber-Castell Pitt artist pen (B) in warm grey, Pentel ink brush, Pilot Hi-Tec-C 0.25 in black, Faber-Castell Pitt artist pen (F) in black, and a black Pentel brush pen.
Oh, and the watercolors don't fit in my bag, so I need to figure something out there.
jetpens.com. I think Toby bought it for me because the top is orange, but it just happens to be a FANTASTIC fountain pen for writing and drawing. This is the fine point, and I've since purchased a medium point, too.