Instead of paying the minimum amount once a month, pay half that amount every two weeks. This could save you thousands of dollars on interest by faster reducing the monthly balance on which the interest is charged.
 

For example, say you owe $3,500 at 17 percent and your minimum monthly payment is $70. If you pay only the minimum each month, it will take more than 25 years to pay off the $3,500! And by that time you will have paid more than $7,200 in interest!!! But pay $35 every two weeks and you'll cut your over $5000 in interest and be debt free in just seven years. Naturally higher than minimum payments will cut your debt even faster.

When paying your mortgage pay a regular payment and then in the middle of the month, pay a little extra ($100-400 ) to get the principle down quickly.  This can get a 30 year loan paid off in 12-18 years.  The Reason: When you pay just your bare minimums, it means 99% of the first year or two of payment goes strictly to interest.  Ask your bank to apply each of your payments within 24 hours.  What you don't want is the bank to wait until next month (and have the interest acrue).