We utlize a credit report service that will run what is called a 'Score Wizard' that will tell us exactly how to bring up your credit scores MAXIMALLY.
The first step would be taking your information and a major credit card to run the credit.
Then we decide how much of your liquid funds you want to apply toward your cards to improve the credit. We then take that amount and input it into the Score Wizard. The wizard tells us exactly (to the dollar) you are to pay down your credit cards AND will tell you exactly what your score will be after those payments are applied.
Once the payments are applied, you provide the current statement (must have both the account number and your name appearing on the statement).
We then have the credit agency verify the balances with the credit card company and that info is forwarded onto the bureau or bureaus that you want to have rescore your credit.
The cost for this about $100 per line of credit per credit agency (Equifax, Experian, TransUnion).
As lenders, we look at the middle of the three scores. I try to focus on one of the three agencies so that we can keep that cost down to a minimum for you.
First and foremost, thank you for posting your question here at trulia. To maximize your credit score, pay off or pay most of any credit card balances. Also, pay before it is due because one is penalize for not paying on time. This will definitely help your credit score.
Going deeper on the credit card theme, be sure to keep your accounts open for at least two years or more to long standing pay history. And don't write into the credit card company to close the account - it doesn't look favorable by the credit bureaus...
Need more specifics, let me know.