Gather your personal financial statements and evaluate your finances. Can you really afford a mortgage on a home? Does that translate on paper? You will need to prove that you can, in fact, pay a mortgage every month faithfully, so your personal financial statements such as income, debts going out each month, tax forms, etc. need to reflect your ability to pay the mortgage at the time you are applying for a home with no money down.
Call numerous mortgage lenders and ask about no money down programs. Such programs still exist, but it may take considerable time and effort to find a lender who will work with you on a no money down mortgage. Ask about "103%" mortgages; these allow you to bundle in closing costs. Every bank or mortgage lender handles "no money down" mortgages in a different manner, so ask for specific information to understand procedures before making any commitment.
Meet with mortgage lenders in person and take all of your financial paperwork with you. Be pleasant, polite, and well-mannered. You're making an impression, and lenders want to know that they are lending money for a no money-down home purchase to a person who will fulfill his or her commitment.
Clean up your credit report if you have any problems on it. Some online sites such as CreditBoards and FatWallet have forums where you can talk to other people who have extensive experience managing poor credit and rebuilding their credit to a healthy level.
Pay off as much debt as you possibly can, or call credit card companies to request lower interest rates. You need to look as credit worthy as possible.
Try AmeriDream's no-money-down program. AmeriDream is a non-profit organization that helps people to get into homes with very little, if any, money down, as does the Nehemiah Program.