Generally, one of your stats must be high, tho' Shady has said, iirc, that you can pass if they aren't that low. Generally, I myself just go for intelligence and max that out + getting animal transformation, where it makes Exams and the first trial easy. I've just focused on intellect - which just made it a need to just pick the correct option for Intellect, which pretty much found no failure
You might be able to get a high enough intellect stat if you do the subject for it, or study every day, or every second day for when it stops. I myself always rotate the classes and don't do the double-stat ones, while slow, it ensures that my other stats are improving. Yet for when the exam and first trial ends, you can, even if you just went full-study, begin doing every other stat for the time between it and the second trial, which should be enough time to ensure you meet some more of the cast, and get it high enough