If you’ve got a low credit score, don’t be embarrassed: You’re not alone. According to a recent Credit Karma survey, nearly seven out of 10 Americans ruin their credit scores before they turn 30. Odds are at least a couple of your buddies can relate.

Let’s take a step back. Why does your credit score matter?

• The higher your credit score, the more favorable interest rates you can get on a mortgage and other loans (e.g., a car).
• Folks with high credit scores get credit cards with higher limits.
• They’re also able to carry the best credit cards in their wallets.

Your credit score suffers when you open a zillion accounts and max your cards out without the means to pay them off. But you already know that.

What you might not know is that you hurt your credit score when you do the following.

1. Forget to pay your bills

Your payment history accounts for 35 percent of your credit score. Missing even one payment can do serious damage.

Get in the habit of paying off all of your bills in full each month. Lenders will take notice, and your credit score will climb.

2. Refuse to use credit cards altogether

Having credit cards — and paying them off on time — is a surefire way to boost your score.

Some people are afraid of credit cards because they fear they'll run up massive bills and dig themselves into financial holes from which they may never emerge. Just live within your means, and you'll avoid suffering that fate.

3. Close credit cards with high limits

Your credit card utilization percentage matters. When you close cards that have high limits, your credit score can take a hit.

For example, let's say you have two credit cards, one with a $15,000 limit, the other with a $5,000 limit. You have $1,000 outstanding on your smaller card, which represents a 5 percent credit card utilization rate on your entire $20,000 limit.

Now, let's say you decide to close the $15,000 card. All of a sudden, your utilization rate pops to 20 percent, since you only have a $5,000 limit. Your credit score takes an unnecessary hit.

Don't do it.

4. Co-sign on someone else’s credit

There’s a reason you’re being asked to vouch for someone. Don’t do it, unless you absolutely must.

When you co-sign a loan, you incur virtually all of the risk without any of the reward. If payments aren't made, the lender goes after you first.

5. Ignore the fact credit scores exist in the first place

How you manage your finances matters, too, whether or not you want to believe it.

The good news is that it’s not impossible to rebuild your credit score. People do it all the time.

It might take some persistence, but if you stick to your guns, you can hit 600, 700, and beyond.

Here’s how:

• Ask your parents to make you an authorized user on their account.
• Apply for new credit cards. Grow your aggregate credit limit — but slowly, and within reason.
• Pay off your student loans and other debts.
• Force yourself to pay every bill on time. Slowly but surely, your credit score will inch up.

If you want a more flexible financial future, you need to take steps toward improving your credit score today. It’s as simple as that.

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