Refinancing may not be that useful if you have already used up 90% or more of your home value in taking out a mortgage or any home equity loan. You won't be able to get the best rates available in the market as when you refinance a 90% LTV loan, you will probably require a loan of that value or higher. This will be quite closer to being a 100% financing option and hence mortgage refinance rates will be comparatively higher. Moreover, 100% loans are hardly available in times of mortgage market crisis.
Get your interest rate and closing costs in writing as soon as you decide on a lender to work with. Get your lender to give you a commitment in advance of all of the costs that will be involved with your loan. Find out if the refinance loan you are getting has a pre-payment penalty as well. Sometimes lenders will leave out important information like this, if they think it might scare you away from refinancing with them.
If there are only a few years left on your current loan, it's no use refinancing with a long term loan. You may need extra cash but with a long term loan, you'll end up paying more for the entire loan term.
Weigh the costs carefully of how long you will be staying in your home vs. how much of a savings you will be getting in a refinance. Make sure you include closing costs in your decision.