Your credit report and FICO score are generated based on your payment history, amounts owed, credit history length, new accounts opened, and types of credit used. Payment history makes up 35% of the score and factors include how much is owed to companies as well as payment history for utilities, medical bills, and rent. To improve your FICO score, pay all bills on time, avoid opening multiple new accounts unless needed, keep balances low at less than 25% of the credit limit, and review your credit report yearly.