If you are selling your home in the fall or winter months
One of the easiest ways to add brightness to your home is with lights. Adding more lamps to your home to brighten up those dark corners can work wonders; extra lamps are particularly nice if they have a tri-light switch in them so that you can add a little or a lot of light to a room. In the kitchen area, you can also add strips of LED lights or under-cabinet lighting underneath the cabinets.
Another way that you can add more light to your home is by lightening up on your window coverings. Consider using a sheer curtain under your heavier drapes so that you can keep the drapes pulled back and let the light cast a glow through the delicate sheers.
A more labour-intensive solution to a home that is dim is that of adding skylights; this solution definitely takes more time and money but can really add some brightness to your home. You can get skylights that have a UV coating so that they won't make your home too hot in the summer months as well.
A different way that you can brighten up your home is by painting the interior in light, bright tones. Too much dark colour in a room can make it seem oppressively small and cave-like; try painting your walls and ceiling in a lighter tone to see if that opens up the room.
In rooms that have the space for them, large mirrors can also help open up the space and add needed light to an area. Hang large mirrors over the mantle in the living room or over the sideboard in the dining area; be aware though that not everyone likes to be able to see themselves eating so try hanging the mirror at a level where you can't see yourself well from a sitting position at the table.
No matter what solution works best for you, it is worthwhile to experiment with ideas to find what works best to draw more light into your home during this darker season. Prospective buyers will look more favourably on a home that feels bright and welcoming over one that is dim and foreboding.