If you have had credit problems, be prepared to discuss them honestly with a mortgage professional. Responsible mortgage professionals know there can be legitimate reasons for credit problems, such as unemployment, illness, or other financial difficulties. If you had a problem that's been corrected and your payments have been on time for a year or more, your credit may be considered satisfactory.
If your credit is already damaged or one of the above isn't an option, go through Consumer Credit Counseling Services (CCCS). Check your yellow pages for the local number. CCCS may be able to help you pay off your debts as if you were in a Chapter 13 bankruptcy, but you don't actually file for bankruptcy.
If CCCS won't take you, you may want to consider bankruptcy. Claiming Chapter 13 bankruptcy takes longer than a Chapter 7, but your credit will end up in a little better standing. Chapter 13 bankruptcy gives you up to 5 years to pay off your debts. The disadvantage is that you're in bankruptcy for up to 5 years plus your credit report shows your bankruptcy for 7 more years after you have finished paying off your debts.