Paying regular extra payments on your principal will yield enormous savings. You can do this in various ways. Paying a single additional full payment one time every year is probably the easiest to track. But some folks will not be able to afford such a large additional expense, so dividing a single extra payment into 12 extra monthly payments is a great option too. Another very popular option is to pay half of your payment every two weeks. The effect here is that you will make one additional monthly payment each year. Each option produces different results, but they will all significantly reduce the duration of your mortgage and lower the total interest paid over the duration of the loan.
It may not be possible for you to pay down your principal every month or even every year. But it's important to note that most mortgage contracts will allow you to make additional payments at any time. Whenever you come into extra cash, consider using this rule to pay a one-time additional payment on your mortgage principal.
If, for example, you receive an unexpected windfall four years into your mortgage, investing a few thousand dollars into your home's principal can significantly shorten the duration of your loan and save enormously on interest paid over the duration of the mortgage loan. Unless the mortgage loan is very large, even modest amounts applied early can produce huge benefits over the duration of the loan.