Here's a drawing I did of dappled summer light on a farmhouse, done in graphite pencil and gray watercolor wash.
This is a very traditional way to sketch, a tried and true technique. And it's a technique that I would recommend for beginners who want to ease into water media, or anyone who doesn't want to carry a lot of stuff. All you need is a little jar of water, a rag or paper towel, a paintbrush, and a couple of graphite pencils, maybe an HB and a 2B, and an eraser.
There are many ways to approach pencil and wash, but I like to use the wash for tones up to about a 40% gray where I need flatness of tone, such as a sky or the shadow side of a building. The parts of the building that you leave white really pop this way.
With the regular graphite pencils, you should be able to add the washes over the pencil without disturbing it, so you can do the pencil drawing first. But I tend to do a light but accurate layin and then add the washes, and when they're dry, I add the darker and softer pencil strokes.
|Rendering of a proposed dining room by Otto Eggers from Guptill's book.|
As for the surface, drawing (or cartridge) paper tends to buckle if you add anything more than a few light washes. If your washes are large or wet, you might want to use Bristol board or a watercolor sketchbook.