I remember turning 18 and getting plenty of “you’ve been approved” credit cards in the mail. I was too scared at the time to get a credit card because I had seen just as many “are you in credit-card debt?” commercials on TV. The thought of owing thousands of dollars from credit card debt scared me. The funny thing was, when I actually tried to get my first credit card, it was a nightmare. I couldn’t get approved because I didn’t have credit. Go figure.

Along the way, I’ve slowly figured out how to use credit cards carefully and safely. The whole point of credit cards are to build credit and they are also good for big emergencies when you may not have a lot of money on hand. I wish I had learned all of this information sooner so that I could have gotten a credit card sooner. Part of your credit score is how long you’ve had a credit card (I’ll get to the credit score part in a second).

Before I get into the little details of credit cards that I have learned so far, there is one thing I cannot stress enough. It may be a “duh” tip but unfortunately, people tend to not follow this rule. Here’s the first tip: always pay off your credit card in full, every month. A way to help with paying it off in full every month, is to treat your credit cards like cash. If you won’t have that money to pay it off by the time the bill is due, do not use it. Yes, it’s tempting when you have thousands of dollars available that second, but will you really be able to pay it off in full? If the answer is no… then don’t use it. Yes, it is as simple as that.

The reason why it’s so important to pay off credit cards in full is because it’s the interest that will lead to terrible credit card debt. Let’s do some math for a second. My current credit card has an interest rate of about 13 percent (or up to 25 percent! It all depends on the person’s credit score). Let’s say I rack up $1,000 on my credit card. My minimum payment is $35. Maybe this month I don’t have $1,000 so I decide to only pay the $35. Awesome. Maybe next month I’ll have enough to cover the rest. Except… that would mean I couldn’t use my credit card. Because if I do, I’ll be racking up even more money I have to pay off. Let’s say, I think I’ll have more money so I rack up another $1,000. By the end of the month I owe $1,000 from this month plus $965 from the month before. Except… the interest rate of 13 percent was added on to the $965 which adds an extra $125.45. So instead of paying off the $1,000 like I should have, I have to pay a total of $1,125.45, plus the $1,000 from this month, and that’s only if I end up paying it all off. But if I continue to pay off the minimum, I’ll acquire more and more interest on my due amount.

Here’s a fun story that might scare some of you from not paying off your credit cards. I have a friend who had someone they knew use their credit card without their knowledge. They finally got numerous calls about an unpaid balance, which was weird to them since they were never the kind to never pay off a credit card. Apparently the credit card had $6,000 that went unpaid for a long time, since they didn’t know about it. So, after all of the interest, they ended up owing about $10,000. While this wasn’t their fault, it still shows what can happen when you don’t pay off a credit card. And the worst part about it was that it brought down their great credit score.

Another tip I actually just recently learned was to try and use only about 30 percent of my total balance. It never looks good to max out a credit card. Especially if you have a high limit, credit card companies will think you won’t be able to pay it off. If you use more than about 30 percent of your limit, you can always ask for a higher limit. I tried for a while to increase my limit to a card and they just wouldn’t. Until, I mentioned the 30 percent rule. They appreciated that I took that rule into consideration and finally increased my limit.

After learning so much about credit cards, I think credit cards are a really great thing. You need a good credit score if you ever want to get a loan or even something as simple as renting an apartment. My roommate and I both have a great credit score so it has always been easy for us to get an apartment. A few years ago, we actually beat out a few families for a house because we had better credit scores. Good credit scores show you’re responsible with money and know how to handle it.

I use credit cards for every single purchase. The way I see it, why would I use cash when I could be building my credit? And also, the best part about credit cards (if you use them correctly) is that you get cash back! You don’t get cash back when you use cash. Most credit cards offer some sort of cash back incentive. My card now gives me three percent cash back (up to $6,000) at grocery stores, then it’s one percent. I also get two percent cash back at gas stations and some department stores and one percent on every other purchase. While that’s not a very high percentage, it’s better than not getting anything back, like when you use cash or debit cards.

The other thing I really like about credit cards is that I’m not as worried about fraud. When someone gets access to your debit card and uses it, that’s your personal money, that you won’t get back until you fight it. I had that happen to me twice, and both times it was for over $400. It was a hassle to get the money back. But with credit cards, that’s technically not your money. And, depending on which credit card you have, the better cards will alert you of fraud right away.

Credit scores are compiled from a few different factors including: how long you have had credit accounts (cards, loans, etc.), your payment history (how well you pay on time), how many accounts you have (the more the better, but only if you can handle them responsibly), credit card utilization (the percentage you use, remember the 30 percent rule?), derogatory marks (any bankruptcies, collection accounts, foreclosures, etc.), credit inquiries (if you’ve applied to many credit cards or loans in a short amount of time it looks bad).

The three factors that have a high impact on your score is credit card utilization, payment history, and derogatory marks. The others don’t matter as much, they don’t necessarily hurt your score too much or help too much either.

Here’s my final advice. Get a credit card if you know how to use it correctly and will pay on time. Yes, emergencies happen, but that should be the only exception. And no, that $500 purse does not count as an emergency.