bad credit mortgage loans 2009

Question about Improving credit?

My credit score is 568, my husbands is even worse. We currently own our home and would like to buy a new one next spring/summer. Our credit score is so bad from not paying on time or even at all. Since March of 2009 we have been working paying things off. Three months ago I got a car loan and I have paid that on time each month. We have no open credit card and the only thing that we pay each month that is reported is our mortgage (in his name) and our car ( in my name). Is there any other way to improve our credit so that in the spring it will be high enough to buy a home?
Edited to say: to the poster below me, your right, I probably should open a credit card to help with paying things on time. But do you think I would be able to get one with a credit score of 568?

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