Recognize that time is on your side: The longer you’ve held an account with a good record, the better your score.
Don’t worry about your credit “mix”: Having a mix of credit means you have revolving credit, such as credit cards, as well as installment credit, such as a home, car or furniture loan, and are handling both types well.
Nix the co-signing: If you co-sign for a card or loan, it’s added to your credit report just as if it’s yours. And that debt is included in your debt load if you apply for credit or a mortgage.
Use the cards occasionally: If you’re not using credit — your house and car are paid off and you don’t use your cards — then there is no activity for creditors to report to the credit bureaus to generate a score.