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Are you eagerly awaiting your 21st birthday so you’ll be of legal drinking age? That’s also the age when you can open a credit card account without a co-signer (unless you can already demonstrate your ability to make payments). That’s just 1 of the things about credit you should know.

Here are 5 more must-knows:

1. The credit reporting industry is already watching you

Have you ever signed an apartment lease or paid for smartphone service or a utility and forgotten about it? “Small, unpaid financial responsibilities can end up a collection on your credit report, a negative mark that affects you for at least 7 years,” warns John Ulzheimer, credit industry expert and guest lecturer at the University of Georgia’s Money Skills for Life class.

Barry Paperno, former FICO consumer affairs manager who now runs the blog SpeakingOfCredit.com, adds, “Even with no intentions of using credit cards, buying a house or needing an auto loan soon, know that landlords and employers may already check your credit and make decisions about whether to hire you or rent to you.”

2. You should check your credit report often

View your credit report before applying for jobs, apartments, credit cards or loans.

“Student loans, credit cards, late payments, unpaid bills or debts and even mistakes listed there could cause you to be turned down on an application,” Ulzheimer says. “Confirm your personal information, debts and public records are listed correctly and monitor your credit report and score monthly with 1 of the free online services.”

If you find no credit files in your name, know that it’s easier to build good credit from no credit than from bad credit, Paperno says.

How well do you use credit?

Good use of credit

  • Checks credit report and credit score often.
  • Uses 1 credit card responsibly.
  • Pays all bills by due dates every month.
  • No balance or small balance on credit card.
  • Saves cash; has an emergency fund.
  • Aware of student loan payment dates and pays on time, when applicable.

Bad use of credit

  • Never checks credit report or credit score.
  • Uses no credit cards or uses many credit cards.
  • Makes late payments and has other unpaid debts.
  • Carries balances higher than 35% of total credit available.
  • Charges emergencies on credit card; no savings.
  • Ignores student loans or misses payments and deferment dates.

3. Just get 1 credit card at first

Once you have a job, a credit card is easy to use, provides fraud protection and can help build good credit, Ulzheimer says. Even using a secured card or being an authorized user on someone else’s account can help build good credit when you charge small, regular purchases and pay the balance before the due date.

Compare credit card rates at Bankrate.com.

“Charge only what you would normally buy with cash such as a recurring cable bill or groceries and never treat the due date as a suggestion as late payments and high balances are the quickest way to debt and poor credit,” Ulzheimer says.

4. Save an emergency fund to protect your credit

Charging emergencies, such as car repairs, home repairs and medical bills, can build up your balance and make even minimum payments difficult, harming your credit.

Instead, work toward saving at least $1,000 in emergency cash — as a start — instead of relying on a credit card.

5. Student loan debt can help build good credit

That’s if you always pay on time. But student loans contribute to bad credit for a long time if you miss payments, default or often pay late, so keep track of payment dates and deferment rules.