Payment history is the biggest factor for your credit score.
Payment history determines approximately 35% of your total credit score. Credit cards, auto loans, and mortgages are common obligations that will be monitored on your credit and tend to report every month. If you are late once on one of these bills it will likely have less of an effect than if you are late several times or on several different accounts.

Your open balances determine approximately 30% of your total score.
It’s not that you owe a lot of money or just a little money, it’s how much of your available balance you are using. If you have a $10,000 credit limit, and you have accrued a $1000 balance, you are only using 10% of your available credit line. However, if you have a $1,500 credit limit and you are using $750, you have already used half of your available balance and this can decrease your score.

Length of credit history contributes about 15% of your credit score.
If you have had established credit for ten years, your likelihood of paying on a new loan is much easier to determine and will, with good payment history, give you a higher credit score than if you have only had credit for a short time.

New credit impacts approximately 10% of your total credit score.
If you are going to apply for credit try to make all of your credit inquires within a short period of time and limit them to only a few. These inquires will look like you are just shopping for a good rate. For example, if you are trying to buy a car, it would be wise not to have ten different dealers run your credit, or even five different dealers over a month and a half. Try to keep this all in a short time frame(less than a month).

Finally, the types of credit also can affect your credit score.
Much like your retirement account, you should diversify your credit portfolio by having a mix of installment credit and revolving credit. A few credit cards that have a low percentage of their max available amount currently owed, an auto loan, and a mortgage that you can afford would be a great start.