Here's a pic of my traveling art supplies. I have a small cosmetics bag filled with several brands of watercolor pencils (I once had one of those kits but have been replacing the colors one-by-one and buy what I can find locally), Dewert Graphitint Pencils, a few drawing pencils, and some erasers. In the main bag I carry a small jar of water, with screw on lid, brushes, technical pens and my water color palette, the portable one, and last but not least my Paperchase journal. For watercolor in my journal I back the page I'm painting onto with waxed paper.
Sometimes I even take my box of Caran d' Ache crayons with me into the field, I have the big box of 60 Neoart Aquarelle's (these are very creamy) and the big box of 84 Neocolor II. I typically take these when I'm going to be very close to my vehicle, or inside of it like when I go to the prairie to draw and paint the buffalo.
And of course I have my digital camera with me, you never know when an opportunitiy will arise.