One of my best girlfriends is in the market to purchase her first home with her new husband, and before applying for their loan she called to ask a question about her credit score. She wanted to know whether or not it was a good idea to open a new Amex card — she and her husband are antsy to start earning points. I answered her question the best I could; the answer is below, along with three other facts about credit scores.

1. Generally, you should not apply for new credit right before your credit is evaluated for a loan. The application for a new credit card will instigate a hard inquiry on your credit and ding your score. Even if the damage is minimal, you could be offered a loan with a higher interest rate if your score isn't top notch.
2. All of the credit bureaus use proprietary formulas to calculate scores, and you have to pay for all three scores to determine an average. If you're simply curious about your score and unwilling to fork up the cash to buy multiple scores, get your FICO for about $16 — according to the FICO website, 90 percent of the largest US banks use FICO scores.

To see two more facts about credit scores, read more.

3. Paying your bills on time carries the heaviest weight (35 percent) in your FICO score calculation; outstanding debt makes up 30 percent; length of credit is 15 percent of your score; any new credit and types of credit used are weighted at 10 percent, respectively.
4. The highest possible score is 850, the lowest possible score is 300, and the median credit score in the US is 723. Most lenders require a score of at least 760 to get the best rates.

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