Be Inquisitive. It's your responsibility to make sure that you understand the terms of your loan. Ask questions and listen carefully to the answers. Don't sign your loan documents until you are satisfied with the information and confident that you have made the right decision.
Be Realistic. Lenders have tightened up loan requirements, so you'll need a good credit score and at least some equity in your home to refinance. To figure out how much equity you have, subtract the total amount that you owe on all of your existing mortgages from how much you think your home is worth. If your credit is severely impaired or you owe more than the value of your home, you probably won't be able to refinance right now.
If you have bad credit, find a lender who is willing to work with you and offer you reasonable loan terms.
If you are refinancing from one ARM to another, check the initial rate and the fully-indexed rate. Also ask about the rate adjustments you might face over the term of the loan.