Get out that mop and get ready to wax because a good floor cleaning will not only look great, but glossy floors will actually add a brighter glow to your home. Polished floors reflect light. Carpets absorb it. So, if you have a lot of carpet in your home, you might want to remove some of it and put down some hard floors. They're easier to clean and help add light to your home.
So, take a walk through your home and see where you can implement some of the less time consuming tips listed here, such as waxing the floors, adding mirrors, and changing your drapes. See how your home feels at that point and then start thinking about how much more light you need and what is the best way to get it, either through replacing old windows with better positioned ones, adding tubular skylights, or changing the color scheme of your home. Have fun with it and good luck!