I've read plenty of articles on how my credit score is determined and what I can do to improve it, but I never felt that this advice was specific enough to answer all of my questions. Well, while shopping for a mortgage, I came across this 20-page PDF document published by myFICO that explains many more of the intricacies of credit scoring than I previously knew about. It even includes specific examples of fictional people's situations to help you understand how scoring works. This virtual pamphlet is written in clear language that the average person can understand.
Despite these 20 pages of information, though, FICO is still somewhat secretive about their formulas for calculating scores, so it's sometimes hard to make definitive statements about the impact of certain actions on your credit score.