-Be creative.
-Don't make a house thats 100% gray. In fact, try not to use grey.
-Use 1x16 bricks on the bottom of the walls, and recolor them to be a darker color (ex: walls are blue, lines are dark blue)
-Use as many special bricks as you can.
-Under any circumstances, do not make flat roofs. Those are just ugly.
-Make sure to put 2 layers in the walls so it's a different color inside.
Sometimes I forget one or two of these, but I hope you find these helpful.