I saw I believe your other post about home buying, but you already had a sufficient number of responses for me to post an answer.
Since I don't have access to your report, I can only answer in generalities.
First, your credit score begins to get lower on your revolving credit cards once you Pass 1/3 of your limit. If you are very near your limits, the bureaus will deduct even more points from your scores.
Next, if you have any late payments, collections, charge-offs, or Bankruptcy these will certainly affect your score as well.
Inquiries against your credit also lower your score. Usually about 10 points for each inquiry.
Exception: If you are shopping for a mortgage, and more than one lender pulls your credit, it is Only counted against you once as long as the credit pull is done in a 30 day time frame.
Lastly, if there is anything on your credit that is incorrect, you should address this immediately in writing. The downside however is that it usually takes at least up to 60 days to correct. Once you have chosen a lender, he or she can also help you in this last area. If you can obtain letters from the creditors in cases where there was an error reported on your account, your lender can do what they call a Rapid Rescore. This can be accomplished in a week or so. Additionally, if you are able to pay down any credit cards that are over 1/3 of your limits, with written proof of your current balance from your lender on their letterhead, your lender can also submit this under Rapid Rescore and improve your credit as well.
Hope this helps.
If you need any assistance, or would like a free consultation regarding a new loan, please contact me through my profile with my contact information.
Best of Luck.
Wayne L. Brown
Security National Mortgage Company
NMLS # 343946
Company NMLS # 3116