Brown age spots on the hands can be lightened with a paste made of baking soda and lemon juice. Powdered bleach from a beauty outlet mixed with lemon juice works.
The most popular remedy is to use a cream bleach containing at least 2% Hydroquinone. Rub the cream on twice a day and within 2 weeks you will notice changes.
Spots are caused by repeated sun damage, so for starters you need to begin using a good sunscreen on the back of your hands daily. Fade creams help a little.