How many credit cards is too many? How often should you apply for a new line of credit, especially if you’re interested in taking advantage of welcome bonuses and travel rewards?

In general, we recommend waiting three to six months between credit card applications—but there’s no limit to the number of credit cards you can have in your wallet, especially if you know how to use those cards responsibly.

“Know how credit cards work, know yourself and know what you can handle,” explained Luke Thomas, a 27-year-old public relations manager. Thomas applied for his first credit card at 19—and since has opened a total of 24 credit card accounts. Currently, 16 of those accounts are still active. Thomas has used his credit cards to build excellent credit, fund a Paris vacation and book free flights for an upcoming trip to Puerto Rico.

Here’s what he learned along the way, plus a few tips and tricks that might help you when you apply for your next credit card.

Build your credit as early as possible

Thomas opened his first credit card when he was 19 years old—but he began building his credit history several years earlier.

“I started building credit younger than my peers,” Thomas said. “When I was 15 or 16, my mother added me as an authorized user on one of her credit cards so I would have access to a line of credit if I were in a driving emergency.” Since his mother had a history of using credit responsibly, Thomas piggybacked on that history to start building a positive credit history of his own before he even had his own credit card.

This gave Thomas an advantage when it was time to apply for his first credit card. “I was accepted for the Discover it® Student Cash Back with no problems,” he told us. “The Discover it Student card is a great way to build credit since they don’t give you an outrageous credit limit.”

By making small purchases on his Discover card and paying them off, Thomas quickly learned how to use credit as well as how to take advantage of Discover’s cash back rewards.

How to start building credit

If you want to build your own credit as quickly as possible, here are three tips to help you get started:

  • Become an authorized user. Being an authorized user on another person’s credit card account is a great way to build a positive credit history—especially if you’re not in a position to apply for a credit card of your own.
  • Apply for your first credit card as soon as you are eligible. Thomas took out his first credit card at 19 because that was the minimum legal age to open credit in his home state of Alabama. Depending on state laws and credit card issuer requirements, you may be able to take out your first line of credit at 18 or you may have to wait until you’re 21. Research the rules in your state and try to apply for your first credit card as soon as you become eligible.
  • Choose a good starter credit card. Thomas applied for a student credit card that offered cash back rewards. You may also want to consider a secured credit card that offers a small line of credit in exchange for a security deposit. Pick a card that helps you access the credit you need while also offering the rewards you want.

Learn how to maximize credit card bonuses

Once Thomas started using his own credit cards, he realized that by using cards strategically, he could essentially make money in the form of rewards. While many savvy cardholders apply their energy to optimizing rewards categories for spending on certain purchases, Thomas prioritizes cards offering bonus rewards, especially welcome bonuses. “I did a lot of reading on websites and forums,” he said, “learning strategies for how to take advantage of credit card bonuses without going into debt.”

Thomas started by maximizing the referral bonus his Discover it Student Cash Back credit card offered. “They would give $50 at the time in rewards,” he explained. “I got a lot of my friends in college to apply.”

“When I was in college, I opened two different cards and saved up all of my bonus rewards,” Thomas said. “Then I went to Paris as a graduation trip. My family helped me with the plane ticket but my spending money came from the credit card bonuses.”

Since Thomas’s strategy is focused on earning bonuses, he only spends on one or two cards at a time. “I put all of my spending on whichever card has the bonus I’m trying to get,” he explained. “If I’m in-between welcome bonuses, I like to put my spending on a 2 percent cash back card.”

He also prioritizes credit cards that help him fund future travel. “Right now I’m using a card that earns Delta SkyMiles, because I won’t be tempted to use my rewards for a statement credit.”

The key is to use a new credit card to cover big expenses that you’ve already budgeted for in order to meet the spend requirement for the bonus without overspending. “Find ways that you’re not spending any more money, but you are charging more to your card,” Thomas explained.

For example, Thomas has been able to earn multiple credit card bonuses by putting his rent payments on his credit card. He also paid as many bills with credit as possible and volunteered to pick up the bill when he and his friends went out to restaurants. “I would put it on my card, and they would pay me back.”

Know your limits and stick to them

How does Thomas manage multiple credit accounts? It all comes down to understanding his credit, knowing his limits and avoiding interest.

Understand your credit score

Thomas has thoroughly researched how to use credit cards, as well as how credit scores work. “People think that having a large number of credit cards is bad for your credit score,” Thomas said. “You may take a hit when you apply, but as your credit utilization ratio improves, your credit score should go up.”

Thomas’s credit score recently dropped from 804 to 746 after a few of his unused accounts were closed by the lenders due to inactivity. While this minor credit score dip is unlikely to affect Thomas’ ability to apply for credit in the future, it is a potential consequence of balancing multiple lines of credit at once. In Thomas’ case, the rewards he’s earning on his credit card accounts make the entire process more than worth it.

“I just booked a trip to Puerto Rico with my boyfriend,” he explained. “We’re going in March. He opened a card, too, so we were both able to get free plane tickets and have miles left over for another trip.”

Stick to your limits

“I know my limits, and that if I put money on more than a few cards I quickly lose track of how much I’m spending,” Thomas said. “I think people automatically equate credit cards with debt,” he explained. “Know your limits and have self-control. If you’re not the kind of person who can have 24 credit cards and not be in debt, this isn’t for you.”

Thomas doesn’t have 24 active credit accounts anymore. As of this writing, he has 16 open credit cards, but he canceled three cards because they had annual fees. Although some cards were closed due to inactivity, Thomas makes sure to keep his oldest credit accounts active to maintain a longer credit history.

“With my oldest cards, I make sure to autopay a bill or two so it doesn’t affect my credit history,” he added.

Avoid interest whenever possible

Thomas also makes sure to pay off his credit card bills in full every month to avoid going into debt. “Interest erodes the point of bonuses,” Thomas explained. If you’re tempted to carry the occasional balance on your credit card, think about how the interest you’ll pay on your balance will cut into the rewards you’re earning on the card. Then ask yourself if there’s a way to pay off your balance in full before it starts to accrue interest—and before it has the chance to become credit card debt.

Is a multi-card strategy worth it?

If you follow Luke Thomas’s example and learn how to manage multiple credit cards responsibly, you can earn valuable sign-up bonuses, take advantage of credit card rewards and redeem those rewards for plane tickets, statement credits and more. You might even be able to fund your next vacation on credit card rewards or use those rewards to cover the costs of a round-the-world trip.

If you’re thinking about taking out multiple credit cards, ask yourself what you’re hoping to get out of each line of credit—and how you can achieve your goals without accruing credit card interest or taking on credit card debt.