Credit scores are most important when it comes to mortgages, said Laura Walton, executive director of TCI Foundation, a nonprofit that provides financial education in Tucson, Arizona. When you see mortgage rates falling to new lows, remember that those rates are available only to people whose score tops 760, the top tier of the credit score scale.
The difference in interest rates is dramatic. At the top end, borrowers pay a rate of just 3.285 percent, but two tiers down, borrowers with a score between 680 and 699 pay 3.684 percent, according to myFICO.com.
Read MoreHow hot is your credit score?
For a $300,000 loan, borrowers with the lower credit score would end up paying an additional $800 a year. It may not seem like much, said Walton, but according to myFICO's online calculator, that's $24,000 over the life of the loan.
"If you invested that $24,000 at 8 percent for 30 years, it becomes $91,000," Walton explained. That's a good chunk of change that could finance something significant in retirement.
Ferrari, the realtor, advises homebuyers to pull up their credit scores a few months before seeking preapproval on a mortgage. That way, if there are mistakes on a credit report affecting your credit score, there will be time to clear them up. Consumers could also elevate a not-so-impressive score by making on-time payments on loans or credit cards for a few months and by paying down credit card balances to below 25 percent of the credit limit (keeping in mind that a 0 percent utilization rate could actually hurt your score).