Stick with a simple loan. It is easier to understand and less likely to get you into trouble. Adjustable-rate mortgages may seem like a way to get a bigger house now or to keep more money now, but when the rates adjust you can get into trouble. Avoid anything with a balloon payment. Just choose a simple 30-year mortgage you can easily afford.
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.
Pull your credit report from the bureaus and review it for any negative items (late pays, collections etc) and inaccurate detail. Try to dispute negative items and remove them from the report. If required pay off any unpaid debt. Otherwise, you won't get a low rate and may not even qualify. Of course there are lenders in the subprime market who may offer you a bad credit refinance loan, but it's better to avoid them as they'll possible charge higher rates and fees.
Refinancing can be the right move to improve your financial situation, but be careful. Making the wrong move can put you much worse off. Smart and simple choices will go a long way toward keeping you financially secure.