I asked this question of myself some years ago just as I began my studies in college, working towards my major in English literature. I did two more majors in Theory of Literature and Creative Writing. Now that I know the answers, I have more confidence in regard to approaching the next level of my on-going studies in English Literature. The next step in my studies will be my Masters in English. Of course, to get to that point, I would still need to qualify.
This I did. It was not quite Magna Cum Laude. But I came close. Several distinctions later, I got my university degree. One of the important areas of study during the course of pursuing all three of my majors was the ability to write persuasively, whether preparing an academic essay, writing a literary review paper or preparing a portfolio of works for my creative writing major. To get to master the writing of a persuasive essay, there are no secrets, just simple methodologies formally introduced by our lecturers at the junior level. As a university student, you should know by now that much of the work is now left to you to research your own ideas. And by the way, this short inspirational summary is also of use to high school students, particularly those who love to write.
I hope that my short summary has provided you with enough inspiration and motivation to make your own productive forays in sourcing new ideas and examples of persuasive writing and how you should prepare for it.