According to NerdWallet’s Inaugural Consumer Credit Card Report, millennials have the lowest average credit score of all age groups with 28 percent scoring below 579. When used responsibly, credit cards are the easiest way to build your credit. The problem is, many millennials are hurting their finances by making these credit card mistakes:

Applying for cards without meeting the qualifications

Millennials with credit scores ranging from 300 to 579 are more likely to apply for a credit card and get rejected. You may think your rejection isn’t a big deal and apply somewhere else, but you’re doing more harm than good. With every application, the lender does a “hard” inquiry into your credit history which causes your credit score to take a dip. The more inquires you have, the riskier you seem to lenders. Rather than apply for several credit cards which require excellent credit, look for cards geared towards your credit range and choose the best one.  If you have little to no credit, this may mean applying for a student or secured credit card.

Picking cards based on advertisements and promotions

Almost half of millennials who applied for a credit card, chose one they saw in an advertisement or promotion. Selecting the right card requires more information than what’s presented on TV. While the idea of 1% cashback on purchases and 0% APR is appealing, you’ll receive the shock of a lifetime when your interest rate skyrockets to 22.99% after the introductory period. Save yourself some trouble by doing the proper research. Look for a low interest card that fits your needs and has minimal fees and penalties.

Avoiding credit cards altogether

31 percent of adults between 18 and 34 have never applied for a credit card. While avoiding credit cards is a good way to remain debt-free, you’re missing an opportunity to build your credit. MyFico states that 35% of your credit score depends on your payment history and another 15% depends on how long the accounts have been open. By getting a credit card, charging a few items and paying the total balance by the due date, you’re showing creditors they can trust you. Over time, your credit score will rise, qualifying you for better interest rates on future loans. This will save you a lot of money on interest if you ever plan on buying a house or car.