If you use a credit card, then it’s important to make sure that you are keeping up with your repayments. You should settle your monthly bills in full and on time as late or missed payments can negatively impact your score.
In addition to this, you should try to keep your rate of credit utilisation low. Ideally, you should spend no more than 20-30% of your available credit limit across all your credit cards. If you are using a large percentage of the credit available to you, then that suggests you might be in a bit of financial trouble and so lenders may be less willing to lend to you. This could negatively affect your score.
Essentially, timely repayments and maintaining a low rate of credit utilisation, show lenders that you are able to manage your finances responsibly and are not too reliant on credit.