Age spot removal treatments can cost a lot, but this simple and readily available remedy doesn't. Lemons contain alpha hydroxy acids as well as vitamin C, both of which are common ingredients in expensive creams, peels, washes, and other beauty aids. While alpha hydroxy exfoliates, vitamin C supports collagen production and functions as an antioxidant. (Note that the benefits of lemon aren't limited to topical application... visit the resources section of this article for a link.)
Soak the cotton ball with the lemon juice, and rub it on the area you wish to treat.
Leave it on anywhere from 5 - 30 minutes, depending on how sensitive your skin is. (If you're unsure, start with just a few minutes and work your way up gradually. As with most acid peels, your skin will slowly adjust so that you can leave it on longer.)
Do this however often you like, preferably at night (see warnings section): every day, every other day, or just a couple times a week. Again, this will depend on how sensitive your skin is.