Your credit score is one of the most important numbers you'll carry through life -- like it or not.

No one asks if you want one. No one tells you when you get one. No one tells you what it is unless you pay to find out.

Yet this measure of your money management determines whether your application for a credit card, auto loan or mortgage is approved or rejected. Insurers use it to set premiums and employers look at it when you apply for a job.

Click here to learn more about:

• What goes into your credit score.
• Where to find free copies of your credit reports.
• How to get your credit score.

There are no shortcuts to improve a less-than-stellar credit score. Don't even think about wasting money on credit repair companies that want to "fix" your history for a fee.

To improve your credit score, here's what you've got to do:

Smart move 1. Correct any errors on your credit reports.

Order free copies of your credit report from the three major credit-reporting agencies and read them thoroughly to find errors. Removing inaccurate information can give your credit score a bump in about 30 days and costs nothing but postage. Just mark up your credit report with the errors you found, write a letter that explains the problems and ask the credit bureau to investigate.

Click here for a form letter that tells you exactly what to say and where to send it. Be sure to enclose any proof you have to back up your claims and use certified mail with return receipt requested so you have a record that the bureau received the letter.

Smart move 2. Pay all of your bills on time.

We know you have a lot going on in your life. Bills get misplaced and writing checks is a pain. But you need a system to get every bill to every creditor, before the due date on your statement. (Our "No more late fees" work sheet may be able to help.)

More than a third of your score is based on your payment history and the formula is heavily weighted toward your most recent record. Paying all of your bills on time for just six months can boost your score.

All late payments are equally damaging to your credit score, so do everything on time: pay utility bills, pay parking tickets, and even return library books before their due date.

Smart move 3. Use every credit card you have.

Credit cards that never see the light of a cash register don't contribute to your payment history. Rotating charges among all your cards, and making all of the payments on time, can build a good payment history more quickly.

Smart move 4. Pay down credit card balances.

The next biggest factor in determining your credit score is how much of your available credit you've tapped. If you owe $5,000 on a card with a $10,000 credit limit that means you've used half of your available credit -- and that's too much. Try to keep your "debt-to-available ratio" below 20% on every card.

These calculators can help you find the fastest, cheapest way to repay a single card or all of your cards.

Smart move 5. Don't apply for credit on a whim.

Your mailbox may be full of credit card applications offering low, low rates for a few months. And cashiers often push you to get a store charge card when you check out, tempting you with a discount on your purchase if you'll just fill out their form. But if banks and stores are constantly asking the credit agencies for your credit history, your score suffers. As a general rule of thumb, figure every inquiry costs you 10 points.

Smart move 5. Ask to have a repaid debt taken off your credit history.

If you've mended your past-due ways and brought a delinquent account up-to-date, ask the creditor to remove unflattering entries from your credit reports. You'll have the most leverage if it's an active account that you've paid on time for at least a year. Just write a letter and ask. It's certainly better than allowing a bad debt to sit on your credit report until the agency removes it after seven years.

Smart move 6. Become a co-signer on an established credit card.

The account will appear on your credit history with the original opening date (not the date when you were added to the account) and its entire history of on-time payments. That can add 30 to 45 points to a poor credit score.

But you'll need a spouse, parent or astoundingly good friend who's willing to add you to their account as a co-signer with legal responsibility for the debt. Being an authorized user, someone who can make purchases with the card but isn't responsible for making the payments, will no longer help with your credit score.

By Bonnie Biafore

Interest.com Contributing Editor

Have a question about your finances? Ask us at editors@interest.com