source: I worked at a big bank and did this, it was easy.
Most of the stuff is obvious and intuitive (don't make late payments). One that's not terribly intuitive is credit line utilization. It has a big impact and most people don't think about it. For example, it's better to have 2k in credit card debt if you have 20k in credit lines vs. 1k in debt on 2k in credit lines.
Ever wonder why your credit score goes down randomly in one month despite nothing changing?
FICO’s black box algorithm put you in a newer credit group of higher credit scores. In that group, your profile scored much lower compared to others. Thus you get a 10-20 point deduction.
If you have a long history of good credit it probably doesn’t matter. But if you are a young person looking for auto/home mortgages, that 10-20 pt dedication _could_ lead to slightly higher APRs depending on the underwriters own scoring algorithm.
In fact, FICO even provides you with a tool to "reverse engineer" a credit score given the data.
https://www.myfico.com/fico-credit-score-estimator/estimator