When planning the electrical layout for a dollhouse you need to keep track of your wiring with a wiring layout plan. This printable one is a sheet in pdf (acrobat reader) form , laid out to indicate walls ceiling and floors, ready to be filled in with the wiring diagram for your dolls house room. The easiest plan to use is one which shows each room in the dolls house in a flat plan, as if a bomb had gone off and flattened out the room walls and ceiling.
The act of planning your wiring will help you see where you will have to drill holes, and any problems you may have with sizes of light runs, the number of bulbs on a circuit etc. The sample shown here (also available as a larger pdf file) uses a standard key to show where wires, lights, flicker bulbs/fires and outlets are located. These should be shown in accurate locations on the diagram in case you need to find and modify the wiring at a future date. In addition, it is helpful to keep a record of the lights you have used, or plan to use, along with manufacturer's information in case you need to replace or return them. (see the sample sheet in pdf form above to see how this is used)
Even if you don't plan to add lights to your dollhouse right now, a layout plan for each room will show you where you will have to install wiring now, or risk tearing out the wallpaper and floors at a later date.
These sample layout plans are adapted from some by Martin Butler of Small World Products.