One of the most useful tools, is the drawpad+photograph. All successful design requires that the building is nicely adapted to the site where it is to stand. Even the smallest addition to a building must follow the same rule. A new closet is good, or bad, according to the degree to which it fits harmoniously into its surroundings.
Normal methods of design do not help, because you are supposed to draw, or imagine, out of context—on a drawing, on a sheet of tracing, on blank computer screen. But if you start with a photograph, and draw on the photo directly, the photograph itself leads you to do the right thing, and as you develop or sketch your design, you can continuously adapt it, and make it harmonious with the place.
If you like, you can also see an example of it being done by a user.
In some circumstances you can even work on two or more photos at the same time.