What are things you must do your senior year?

I am planning my last years of high school and am in need of help for all the things I need ready by for and by my senior year. I refuse to get behind and not be ready. What are things I should know? What is the best financial aid? How do I start my resume? What is important for my freshmen year of college? How can I be prepared; and what are some important need-to-knows? Thank you.