The main aspect of debt that affects your credit rating is the balance you carry on your lines of credit. Credit score calculators examine your credit utilization by studying the relation between your credit card balance and your credit threshold. Though installment loans play a part in the amount of debt you have, credit score calculators focus more on your credit card usage.
If you have a high balance on your credit card(s), your score will suffer. On that note, having a maxed out credit card will severely hurt your credit rating.
Make small purchases
It is ok to have a credit card with a high credit limit. However, do not look at the limit as a way to spend more money. At the end of the day, you still owe that money back to the creditor, and you will owe it back with interest. Therefore, only make small purchases that you can pay off at the end of each billing cycle.
Do not close unused credit cards
Allow your unused credit cards to stay open. This will help your credit utilization rating and debt to credit ratio.
Do not open a bunch of new credit cards
Be content with the amount of credit cards you have. If you feel the need for a new credit card, try not to have any more than three at a time. If you desire more credit, simply ask for a credit increase on the credit card you have owned the longest