My credit score is only slightly higher than yours (thanks to poor CC use in college), and my H and I were approved for a loan.
Here a few suggestions:
Use cash or debit card - if you don't have the $, you can't buy it. Also, using the debit card or cash more will help keep your debt to credit ratio low.
Pay extra each month if you can on your debts. I pay $120/mo on a student loan even though the required payment is only $50ish. More of my money is going to principal every month. It really adds up after a while.
Design a budget where you pay yourself first - it's hard, but it's very helpful!
When you think you are ready financially for a house, try simulating a mortgage payment by putting extra money aside each month. For example, H and I pay $1000 for rent. We put an extra $400 in savings each month as if we had a mortgage. This way, we could see if we could handle it, and it also padded our savings!