Credit repair scam artists will charge you anywhere from $500 to $1,500 or more upfront, and promise you everything from a new Social Security card to perfect credit.

But these companies can’t do anything for you that you can’t do for yourself — for free — and they might ultimately do more harm than good.

What should you do if you have bad credit? Here are 10 tips that are designed to improve your credit history and raise your credit score:

1. Pull a copy of your credit history from AnnualCreditReport.com. Sponsored by the three credit-reporting bureaus, Equifax, Experian and TransUnion, AnnualCreditReport.com is the only place you can go to get a truly free copy of your credit history. Each credit-reporting bureau is required to give you one copy once a year. You should pull copies from each of the bureaus, since they sometimes collect different data.

2. While you’re there, buy a copy of your credit score from Equifax.com. Equifax offers a FICO score, also known as a Beacon score, which is from Fair Isaac, the company that created the concept of credit scoring. Most creditors will pull a FICO score, so you should see what they’re seeing. Your credit score will give you a snapshot of what your credit information means to your creditors. The FICO score runs from 350 to 850. The higher the number, the better. Your target should be to have a credit score of at least 720.

3. Check your credit history thoroughly. You’re looking for errors, misinformation and negative information that might count against you. File a dispute with the three credit-reporting bureaus if you spot any errors. Some credit reports have serious errors in them, so fixing these will boost your score.

4. Understand what kind of debt you’re facing. Make a list of everything you owe, the interest rate each debt carries, and the minimum payment due each month. Then, prioritize your debt: mortgage, real estate taxes, credit cards and medical bills should be paid in that order.

5. Negotiate with your creditors for a lower interest rate. Paying less in interest means more of your payment each month goes toward paying down your balance. If you have a good credit score (over 720 is a starting point), you should be able to find other credit cards featuring zero percent to 5 percent in interest for the first year, or for the life of a balance transfer (check out sites like CardRatings.com and CardTrak.com to compare credit-card offers.) Just be sure you read the fine print: Some credit cards require you to charge on the new account each month or face a stiff fee.

6. Pay down the debt with the highest interest rate first. Pay your mortgage and home equity loan and lines of credit in full each month. Then, make sure you have enough cash to make all of the minimum payments due on your debt each month. Then, throw any spare cash at the debt that carries the highest interest rate first. Once you’ve paid down that debt, transfer all of the extra cash you’re paying each month to the debt with the next-highest interest rate, and so on.

7. Pay everything on time, even if you can make only the minimum payment. The most crucial component of your credit history and credit score is your ability to pay your bills on time each month. Paying on time shows your creditors that you take your debts and obligations seriously. Even one late payment can seriously damage your credit history and credit score, even though it can take a year’s worth of on-time payments to start to heal your credit history and raise your credit score. It doesn’t seem fair, but that’s how the credit industry works.

8. Don’t charge more than 25 percent of your maximum available credit limit. If you carry a credit-card balance that is a higher percentage of your available credit limit, your credit score will go down. Why? Because creditors believe if you charge the maximum on your credit cards, it means you can’t properly manage your credit. You’re better off spreading out your debt between three or four different cards than having it all piled on one card.

9. Don’t open and close a lot of accounts. Again, a credit score tells current and future creditors how likely it is that you won’t pay back your debts. It assesses how risky a borrower you are today. Every time you apply for a new credit card, that creditor pulls a copy of your credit history from the credit-reporting bureaus. That “inquiry” gets reported on your credit history. Too many inquiries in a short period of time signals that you may be getting low on your available credit and need more cash. Even though you might be interested in getting 10 percent off your first purchase for opening a new account, it looks different to a prospective creditor.

10. Don’t share credit (except with a spouse). It’s easy to tell someone that you’ll “co-sign” a credit card, student loan or a mortgage loan application, especially if it’s someone you’ve known for a long time. But it’s also easy to wind up in a situation where that friend or relative stops paying his or her bills (for whatever reason) and your credit will take a big hit. Once you’re a co-signer for a loan, you’re legally obligated to make those payments — whether or not you can afford them. So think carefully before you agree to co-sign a loan, and nip the problem of bad credit before it begins.