Your FICO score is single-handedly the most important data point that lenders use to judge your ability and willingness to repay what you’ve borrowed. Just five factors, the most important of which are whether you make timely payments and your account history, make up all the information that the credit bureaus use to determine your FICO credit score.
The nitty-gritty of the FICO scoring algorithm is kept a secret, but the credit bureaus make enough information available to the public that we have a very good idea of how to get the best possible score.