For those who asked how I do brick walls and tiled roofs, here are some demo pictures. I made the files low quality to speed up loading, but I think you'll get the idea. It really is quick when you get the hang of it, and produces realistic results.
First and foremost you must have a selection of cheap craft flat brushes of various widths. I bought a set of 4 for £2.75 (around $4) which vary from 1/4" to 1/2" in width. Here for clarity I am doing it fairly large and I am using a "No 8 Royal 9150 Shader" 8mm wide (around 1/3 inch), but various widths can be used depending on the scale of your painting. You may not want to paint every brick, just groups of bricks which indicate to the viewer how the wall is constructed.
I begin with a background wash - a mixture of colours from my palette applied wet -in-wet for the roof, and a pale colour for the mortar to the brickwork:
Then I draw in the tiles, starting with broken horizontal lines with a ruler, followed by spaced out "verticals" which follow the angle of the edge of the roof: Alternate rows are staggered, just as in brickwork.
Now for the bricks. Using the flat brush and angling the paper so the brush tip lies along the line of the brick courses, I use short downward strokes along each course of brick, leaving gaps for the mortar. The gaps aren't critical, but if they are even so much the better. Each alternate course is staggered so that each brick lies centrally over the gap between the bricks above.
At the edge of the wall, and where windows and doors occur, there is a half brick on every alternate course. I've found the easiest way to paint these is to hold a piece of paper up to the edge to be painted and just simply overlap the brush onto the paper, so only half a brick is painted on the painting:
Where the different colours occur in the roof tiles (at random) I use the flat brush to add a mixture of various colours to add interest to the tiles. Here I've also used the flat brush to paint in the window panes, leaving gaps for the white framework. Shadows were then added to the top and left edges of each pane to add depth:
Here's my palette which has a range of colour variations which add interest to the painting if applied. A similar technique is used for stone walls, and depending on the scale, shadows can be added to the stonework joints to add depth.
Hope you can follow the demo, and why not give it a try?