You can spice up a black and white sketch with a little dash of color. It’s just like sprinkling adobo on a bowl of beans.
When I sat across the street from this corner market in Rincon, Puerto Rico, I worked up the sketch in pencil and gray ink wash. I enjoyed trying to suggest the abstract detail seen through the window. But the sketch needed something to perk it up.
I dug down in one of the pockets and found a yellow marker for the fire hydrant and the “escuela” sign.
If you carry a red or yellow colored pencil or marker along with the rest of your sketch set-up, it just might come in handy for a spicy little accent.
More on the "line and wash" technique, link