Phone your watch dog. If your best deal is through a broker you don't know, call your state banking department. Ask if the broker is registered or licensed. Some departments can tell you how long a lender's been in business, how many loans it's arranged in the last year or two, and whether there are any consumer complaints on file. Check references with a few homeowners, too.
Applications are costly.
Patently unjust though it may be, most lenders charge potential customers for the privilege of being evaluated as borrowers. If there's a non-refundable application fee, make certain that your financial situation is well within the lender's limits for approval. There's more than one way to skin a fee. Ask if each closing cost can be waived, reduced, or handled differently. And be sure to find out if you're eligible for any special discounts.