A common mistake that people make isn’t using credit cards. Putting them away in a drawer doesn’t hurt your score, but it also doesn’t help. Instead, spend between 1% and 30% of your credit line each month. If possible, pay the balance in full. Otherwise, make the minimum payment. That alone will make a substantial difference in building your credit.
As an example, if you have a recurring bill that can be paid using credit, use your credit card. As soon as the credit card statement arrives, pay it off. Not only will that help build your credit, but you’ll also avoid any fees. Ultimately, it would cost you nothing to use the card for this type of expenditure.