Second mortgages are a popular way for homeowners to get approved for a loan. If you are sure you will be able to pay back the loan, it can be a fairly secure financial decision. However, you should do some homework and serious number crunching before signing on the dotted line. Knowing your equity and credit history will help you find the lowest interest rates and fees. You can also calculate how much money you can expect to borrow based on your equity and the appraised value of your house.