The best way to tell if you have any chance at Princeton is to compare your stats with the current Freshman profile 2016. If you are within range, then take a look at the decision threads from last year to see what makes the accepted students standout. In general, all schools like Princeton have more very competitive/qualified applicants than spots, so there is no “magic” formula to get an acceptance.
https://admission.princeton.edu/applyingforadmission/admission-statistics