Teeth whitening is a simple proposition.  A whitening agent, usually some form of  peroxide is applied to  your teeth, and bleaches them.  The hard part is keeping the agent in place.  There are four basic options:  whitening strips,  paint on gels, laser bleaching and bleaching trays.  The first two are inexpensive and easy, but not very effective.  Laser is very fast and effective, but expensive, and can cause painful "zings" for 24 hours after the procedure.  Custom-fitted bleaching trays are my favorite. You bite into a squishy mold, send the impression off to a lab, and they send back thin teeth covers – one for your uppers and one for your lowers, that you put the bleaching agent on and slip over your teeth.  And you don't need to spend $500-600 to get them from your dentist.   You can order them online.  The company that sold mine is out of business, but all of the kits are pretty much the same.  Search for one online.  I found a great custom tray bleaching system for under $90 at Overstock.com.