'Serious delinquency, derogatory public record or collection filed'

What it means: This can mean that your credit report includes a bankruptcy, judgment, tax lien or collection account. Bankruptcy remains on your report 10 years from the date you file (seven years for a completed Chapter 13). Paid judgments can be reported for seven years, but unpaid judgments can stay even longer. Paid tax liens are removed seven years after being paid, but unpaid tax liens can remain on your report indefinitely. Collection accounts may be reported for seven years and 180 days from the date you first fell behind with the original creditor, leading up to the account being turned over to collections.

What you can do about it: If the information is accurate, this is also a matter of biding your time and making sure you have as many positive credit references currently reporting as possible. (A secured card may be an option if you can't qualify for a regular credit card.) And while paying a collection, judgment or tax lien won't likely change this factor in the short run, it could result in the public-record item being removed from your report sooner and protect you from being sued for a debt, which could result in additional judgments or collections on your credit reports. If dates are incorrectly reported or payments are not being reported -- not uncommon with collection accounts -- dispute them.

'No recent revolving balances (or no recent bank card balances)'

What it means: This reason may appear when your credit report doesn't include any revolving accounts (usually credit cards), or when all your credit cards closed or are no longer being reported. If you have open credit cards, it may also appear when there are no balances on those accounts.

What you can do about it: Don't worry. This doesn't mean you have to have debt to have good credit. As long as you use your cards from time to time, this shouldn't be a problem. But if you are avoiding credit cards altogether, you'll have a tough time getting a top credit score. Get a credit card and use it occasionally -- even a secured card -- pay it in full and on time, and you should be fine.

'Lack of recent installment loan information'

What it means: Your mortgage was paid off years ago. You pay cash for your cars. You don't have any outstanding student loans. Guess what? The fact that you're ultra-responsible here doesn't help your credit scores.

What you can do about it: The strongest credit scores go to those with a mix of different types of accounts. Does that mean you have to rush out and take out a loan? No. But next time you go to buy a car, you may want to find out if you qualify for 0% financing or a low-rate loan. Or you may want to see if you can get a low-rate personal loan to consolidate some higher-rate credit card debt. On the other hand, don't go overboard. You don't want to pay a lot in extra interest charges.

'Too few accounts currently paid as agreed'

What it means: This reason appears when your credit report does not show enough accounts paid on time relative to the number of accounts with late payments. But if you haven't been late with payments, this reason most likely means that you need more accounts reported on your file as "paid as agreed."

What you can do about it: You may want to think about adding a current credit reference, or even a couple of them over time. If you're having trouble getting approved for a credit card or personal loan, consider a secured card.

'Too many consumer finance company accounts'

What it means: Consumer finance companies make relatively small personal loans, usually limited to a several thousand dollars, and quite often at interest rates higher than those on most credit cards. Consumers who rely heavily on consumer finance company accounts tend to be riskier to lenders than consumers without such accounts.

Click here to become a fan of MSN Money on Facebook

What you can do about it: Paying off these types of accounts will not improve your credit immediately, but it's still a good idea to pay them off as soon as you can, since the interest rates are probably high. Next time you need to borrow, try first to get a standard personal loan through a social-lending website, for example, or from your bank or credit union.

More from Credit.com: