Perhaps professional grade tooth whitening is not in the budget at the moment. While it is ideal you use professionally created custom teeth whitening/bleaching trays you can opt for a more affordable option that will take a shade of yellow away. Due to their acidic content, strawberries in replacement of carbamide peroxide teeth whitening gel can effectively whiten your teeth.
How to whiten your teeth with strawberries:
Step 1: Mash 1 strawberry in a bowl with a fork
Step 2: Add a half a teaspoon of baking soda with the mashed strawberry
Step 3: Mix together
Step 4: Dip your toothbrush into mixture and brush teeth
Step 5: let strawberry/baking soda mixture sit on teeth for 5 minutes and rinse