Be Inquisitive. It's your responsibility to make sure that you understand the terms of your loan. Ask questions and listen carefully to the answers. Don't sign your loan documents until you are satisfied with the information and confident that you have made the right decision.
Don't fall for the 0% apr unless it fits in with your master plan. A lot of brokers will try to get you locked into a low interest rate that will balloon on you in a couple of years and leave you out on the street.
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.
If you have bad credit, find a lender who is willing to work with you and offer you reasonable loan terms.