What the credit score includes

Not just the negative credit information such as late payments and bankruptcies, but all credit information stored in the repository's credit files on you at the time of the request.
Past payment performance 35% of the credit score weight

The fewer late payments, judgments, liens or collections, the better. Zero negative entries on your report usually indicate a lower risk.

Recent late payments are more indicative of future default by you than those that occurred more than 24 months ago.

A 30 day late payment by you today will have a greater impact on your score than a bankruptcy 5 years ago with clean credit since.

Credit utilization 30% of the credit scores weight.

Low balances on several credit cards are better than high balances on a few cards. Balances on your cards should be kept at or below 30% of the available maximum credit limit.
 
Too many credit cards can be detrimental.
 
Warning: Do not discuss any of your accounts without first discussing your complete credit card profile with your mortgage/banking professional.
 
Credit history 15% of the credit score's weight  
The longer the accounts have been opened and in good standing, the lower the risk indications are about you.
Opening new accounts and closing your seasoned will negatively impact your credit score.
Avoid credit surfing.

Established credit history is relative to your past payment performance and how high or low your credit usage may be. Self discipline in utilizing credit shows lower risk.
A short credit history does not actually indicate that you are a high credit risk, as long as you are not a heavy user of credit and your payments have been made on time. Keep your balances on cards low! To get a credit score, you should have one account that has been opened for at least six months.
 
Types of credit in use 10% of the credit score.
Finance company accounts will score lower than the accounts you secure through banks or department stores. If the predominance of your accounts is with finance companies only, it may appear you cannot qualify for a better credit.

"90 days same as cash" and deferred payments generally are funded by finance companies, so this variable is a week indicator for the average consumer.
Inquiries on your report 10% of the credit score's weight.

Looking for new credit can indicate higher risk if several credit cards are applied for in a short period of time and your existing cards have been charged to their maximum limits.  
Multiple inquiries, regardless of the number, for mortgage or autos in a 14 day period of time only count as a single inquiry in their impact on your score.  
Additionally, any mortgage or auto inquiry made about your credit file within 30 days of the current lender's inquiry, will not impact your score due to buffers within the credit scoring models.

Promotional or administration inquiries shown on your credit report do not adversely impact your score.  
Only the first seven inquiries made by different trade lines shown on your credit report will actually be factored into the impact on your score.
Only inquiries authorized by you for the purposes of being granted new credit lines will impact on your score.