When it comes to lowering your rates you will need to weight the benefits of having a lower rate vs. paying points up front. You may end up paying a lot more depending on your choice and how long you plan on keeping your mortgage.
For both new buyers and refinancers, it's important to understand what a no-cost mortgage loan or a no-cost refinance loan really means. "No cost" does not mean that closing costs (also known as settlement costs) have been erased. It means that the closing costs will be factored into the interest rate associated with the loan. Of course, this also means that, all other things being equal, the interest rate associated with a no-cost mortgage will always be higher than one where the borrower pays the closing costs up front.
Ask for more than just rates. Bad loan officers will tell you anything to keep you on the phone -- then change the details to suit them later. Instead, make them get real with you! Ask how long they've been in the industry. Probe them about their experience in the industry. Also, ask what their opinion is on the current market and where it's going.
If there is a big difference between the initial interest rate and the APR listed in the ad, it may mean that there are high fees associated with the loan.