When use consistently, homemade teeth whiteners work very well, with two added advantages : you will avoid harsh chemicals and save a lot of money.
You can use these tricks everyday, many times a day.
This way, you will see a consistent gradual change in the color and also maintain your white teeth for as long as you want.
Here are my top 5 inexpensive homemade teeth whiteners chosen for their efficiency and convenience :

1. Peroxide : yes, the little brown bottle that you put on cuts and that bleaches your hair is perfectly safe for your mouth.
   Hospitals use this to disinfect small abrasions in the mouth and it will freshen your breath too.
   Use like a mouthwash.
   
2. Baking Soda : a mild abrasive that will clean your teeth without damage.
   Works best combined with hydrogen peroxide.
   Make a paste and leave on your teeth for a few minutes, then brush of with regular toothpaste.
   
3. Strawberries : the malic acid in the strawberry will work to loosen dental stains crush one strawberry and spread over your teeth.
   Works even better when mixed with baking powder ( but will not taste as good...
   )
4. Bananas : my personal favorite for convenience.
   Rub the inside of the banana peel on your teeth for an instant shine.
   
5. Orange peel : easier to rub on teeth then banana peel and works very well too

Use these homemade teeth whiteners how often you want and mix and match the different methods and ingredients however is more convenient for you.
You will see a gradual whitening effect on your teeth.
Although some of these methods can work quite well for you, please do not expect a drastic change.
For a real whitening effect, you might need a real teeth whitening product.