The following are some helpful tips to avoid the credit mistakes many borrowers make during the loan process:

  1)  DON'T APPLY FOR NEW CREDIT OF ANY KIND including those "You have been pre-approved" credit card invitations that you receive in the mail.  Every time that you have your credit pulled by a potential creditor or lender, you lose points from your credit score immediately.  Depending on the elements in your current credit report, you could lose anywhere from 2-50 points for one hard inquiry.
  2)  DON'T PAY OFF COLLECTIONS OR CHARGE-OFFS during the loan process.  Paying collections will decrease the credit score immediately due to the date of last activity becoming recent.  If you want to pay off old accounts, do it through closing and make sure that a) you validate that the debt is yours, and b) that the creditor agrees to give you a letter of deletion.
  3)  DON'T CLOSE CREDIT CARD ACCOUNTS.  If you close a credit card account it will appear to the FICO that you debt ration has gone up.  Also, closing a card will affect other factors in the score such as length of credit history.  If you have to close a credit card account, do it after closing, and make sure it is a more recent account.
  4)  DON'T MAX OUT OR OVER-CHARGE YOUR CREDIT CARD ACCOUNTS.  This is the fastest way to bring your score down 50-100 points immediately.  Try to keep your credit card balances below 30% of their available limit at all times during the loan process.  If you decide to pay down balances - do it across the board- make an extra payment on all of your cards at the same time.
  5)  DON'T CONSOLIDATE YOUR DEBT INTO 1 OR 2 CREDIT CARDS.  It seems like it would be the smart thing to do, however, when you consolidate all of your debt onto one card, it appears that you are maxed out on that card, and the system will penalize you as mentioned above in 4.  If you want to save money on credit card interst rates - wait until after closing.
  6)  DON'T DO ANYTHING TO CAUSE A RED FLAG TO BE RAISED BY THE SCORING SYSTEM.  This would include adding new accounts, co-signing on a loan, changing your name or address with the bureaus.  The less acitvity on your reports during the loan process the better.
  7)  DO JOIN A CREDIT WATCH PROGRAM.  If you join a credit watch program, you can check your reports weekly or even daily depending on the program you select. (When you pull your own records, you don't get dinged for a hard inquiry.)
  8)  DO STAY CURRENT ON EXISTING ACCOUNTS.  Like your mortgage and car payments.  A one 30-day late account can cost you anywhere from 30-75 points.
  9)  DO CONTINUE TO USE YOUR CREDIT AS NORMAL.  Red flags are raised easily with the scoring system.  If it appears that you are changing your pattern, it will raise a red flag and your score could go down.
10)  DO CALL YOUR LOAN ORIGINATOR if you receive something in the mail from a creditor or collection agency that you believe may affect your score during the loan process.  Your broker may be able to supply you with the resources you need to stop any derogatory reporting to the bureaus. 

Keep in mind that the lender will pull their own credit report at closing and if your scores have dropped, you may no longer qualify for the rate that was underwritten and the final approval may come back with a higher rate.  All lenders use your credit score to determine which loan criteria you fit and every loan has a different criteria attached (the loan-to-value and debt-to-income ratios, etc.)  Many borrowers do not understand this, and mistakenly think the loan officer is "baiting and switching."  If an issue comes up and the lender decides you do not qualify for a certain loan, the only thing a loan officer can do is search for other lenders who might be willing to give the rate and program they thought you qualified for.  If you have good credit and know your score, the loan officer can give you an idea of what he or she can offer based on what you state.  But, do not expect them to stand by their quote if your scores are lower when they pull your credit.