Generally speaking, you debt ratios should be less than 31/43.
In English, this means your monthly housing payment (including Principle, Interest, Taxes, Insurance, etc.) should be no more than 31% of your gross monthly income. Your housing payment and bills together should be no more than 43% of your monthly income.
For example, if you gross $5000 per month before taxes, your total monthly debt should not exceed $2150 per month. Therefore, if your credit cards and student loans are $1000 per month, your maximum housing payment should not exceed $1150 per month.
If you can't buy a house for $1150 per month, then you need to pay off some of your bills or make more money.