I generally use watercolor pencils with a Dove Blender, but I decided that I wanted a more washy look for some beach cards and decided to use a paintbrush with water instead of the blender pen. The stamps used in this sample are both by Stampendous. A few tips - first, use watercolor paper, as it is designed to get a lot of water on it. I used a smooth 88-pound white watercolor paper. Second, stamp the image with an ink that will not bleed with a lot of water. I used Ranger's Archival ink in black and dried it with a heat gun. Third, apply the pencil colors all at once, before you start adding water - you can add additional color from the brush later, but it is difficult to apply color from a pencil once you have introduced a lot of water to the paper. It spreads! See first picture:
Now get a cup of water and a nice soft brush and start blending. The colors will blend very quickly, as you have a lot more water at once than you do with a blender pen. I really liked the effect you can get for the sky - without nearly as much work!
After blending out the color, I cut the cardstock and stamped the wording. I then took the blue pencil and put lines around one side of the words. I blended it out with a paintbrush, then took a white Twinkling H20s paint and added a little pearl effect to the words and the beach surf.
This adds a slightly different look to your watercolor pencils!