Process: Step 2 (color foundation)

Now that I have my pencil layer complete, I need to make one final step in setting up the document for color. If needed, I make sure the image size matches the output resolution requirement for printing (usually I have to scale down a bit), keeping in mind any bleed areas. The document is not flattened so that I can manipulate the pencil drawing. I then add two new layers to the document around the pencil image, one below and one above. Then the pencil layer is set to multiply so that color from the bottom layer can be seen through. At this point, there are many things that can be done to the pencil layer to add some texture. Noise can be added, but I've stopped doing that, because as long as you scan the drawing in color at a high enough resolution, you get nice texture from the paper grain. Nicolas also toned his pencil layer with sepia (Image/Adjustments/Hue-Saturation, then check the colorize button), which I've also played around with and don't really have an opinion either way. It comes down to an aesthetic choice.

Laying down the foundation color:
On the bottom layer, I paint bucket the entire canvas with a warm ochre/sepia of my choosing so I can work on top of that rather than white. Something about a rich warm tone stimulates my imagination better that a blank white surface. It also gives my final palette unity, even if there is no visible sepia in the finished image.

After this foundation color is applied, I start laying in the colors in broad strokes with the paintbrush tool (I play around with different textures of brushes), and working background to foreground, laying in horizon and sky color first. Then, still in the bottom layer, I continue to add more color detail, shading and highlight to each object. I like most of my color to rest in this bottom layer so that the grain of the pencil layer can add texture. This is what the bottom layer looks like in this image:

One final step before the drawing is complete!