Contact your local city code enforcement office before converting your barn into a guest home to ask if you need permits. This ensures you do not obtain a ticket for converting a barn without the necessary permits required in your state or city.
Sweep the entire barn--walls and floor--with your broom. This removes any debris and dirt, creating a clean working surface.
Paint the walls of the barn a light color. Light colors create an open, airy feeling, as opposed to dark paint colors, which create a small look and feel. Allow the paint to dry thoroughly before moving on to the next step.
Place area rugs in the barn to designate different zones. Create bedroom, living room and kitchen zones.
Hook up a generator for electricity in the barn guest house according to the manufacturer's directions. This allows you to incorporate electricity without installing and running an electrical pole and lines.
Place furniture in their designated zones inside the guest house. Create a sleeping area with a bed and dresser, a living room area with a couch and coffee table, and a kitchen area with a table and chair set, microwave and coffee maker.
Set bookshelves in each zone, furnished with useful items. For example, in the kitchen zone, place coffee cups, coffee and dishes on the bookshelf.
Scatter lamps throughout the barn as a lighting option. The generator powers the lamps, creating needed lighting for your guests.
Hang fabric to create an enclosed area for the toilet. Place a portable toilet in the enclosed area.