It's a tough question. There's no simple answer.
The problem is you'll have more than one source of light and they will be of differing color temperatures. The results will likely be warm (yellowish) light from indoor incandescent lights with cool (bluish) light from the windows.
I suspect this will be OK for you except for more valuable properties where potential buyers demand something more professional.
The best, simple answer I can give you is get the widest lens you can, put the camera on a decent tripod, turn on all room lights, set the camera white balance to auto, set your aperture to f11 and shoot a bracket of varying shutter speeds.
But don't forget to call in a professional for the bigger investment properties.
-Pete