This doorway in New Orleans caught my eye because of the shape, shadows, and color. It is the perfect lesson to demonstrate layering.
Layer one: First I transferred a drawing of the door onto watercolor paper. To make this doorway even more fun, I made a full spectrum color wash over top of the drawing. I starting this wash by mixing a quarter size puddle of each color: yellow, orange, red, violet, blue, and green. Don't worry what colors you have - any will do. These were painted down the paper while inclined so that the leading edge of color formed a leading edge of wetness called a bead. Keep adding color to the bead and moving it down across the paper. When color was all over, I picked up the paper, tilted it, sprayed it with clear water in a spray bottle and tilted it back and forth till I got a smooth wash with no lines.
Let the wash dry by laying it flat. You can use a hair dryer to speed up the dry time.
I mixed a turquoise color by mixing Viridian and Cerulean and a touch of green. I put a layer of very transparent turquoise over the door and shutters. To make the paint transparent I diluted it with water.
Layer Three: I mixed a transparent purple of dioxazine purple and neutralized it with a bit of burnt sienna. I brushed on the dark areas of the window panes and shadows. Each window pane should be painted as if it were a separate little abstract painting. I dropped colors in to the panes while still wet to give the illusion of merchandise. After this layer was dry, I went back in with some calligraphic lines that were very dark. My dark color was made with Indanthrone blue and shadow green. I splattered dots of color by picking up very wet paint and hitting it against another brush to speckle the foreground.
All done! Loose and colorful.