Carefully review the estimated closing costs. If you decide to lock in the rate, the lender will send you a "good faith estimate" of your closing costs within three days. Go over the numbers carefully, and compare them to the ones that appear on the final settlement statement (the HUD-1) from your previous mortgage.
When refinancing a mortgage, as many as 30% of homeowner's cash out part or all of their home's equity. By investing in home improvements or paying off credit cards, this can be a smart. But, if you are borrowing more than 80% of your home's value, you will be hit with private mortgage insurance, costing you hundreds a year.
If your monthly payment on a fixed-rate loan includes escrow amounts for taxes and insurance, your payment each month could change over time due to changes in property taxes, insurance, or community association fees.
Resist "no cost" refinancing. No cost doesn't mean free. On the contrary: The closing costs are usually bundled into the new mortgage, which means you pay interest on them. The fees associated with a 30-year mortgage could cost you more than double what they would have had you simply written a check for them at closing. Or, if the costs aren't bundled in, you'll be charged a slightly higher interest rate. Either way, the lender wins.