What kinds of things affect my FICO score?

Five variables affect your score:
1.    Payment history (about 35% of your score). It answers the question, "Do you pay your bills on time?" If you’ve missed payments in the past, get current and stay current. The longer you pay your bills on time, the higher your score. 
2.    Amounts owed to creditors (about 30% of your score). It answers the question, "Do you owe a lot of money to a lot of people?" If you have high balances on credit cards that are close to their limits, your credit score will suffer. 
3.    Length of credit history (about 15% of your score). It answers the question, "How established is your credit history?" If you’re just starting out using credit, your score probably will be lower than someone who has a longer history of paying bills. 
4.    New credit (about 10% of your score). It answers the question, "Are you increasing your debt load?" A flurry of activity and inquiries on your credit report raises suspicion. 
5.    Types of credit in use (about 10% of your score). It answers the question, "Do you have a "healthy mix" of credit?" A healthy mix may include a mortgage, a credit card or two, a personal loan such as a car loan, and perhaps a retail card.