How to re-learn the math I forgot from school, and learn how to do math I never learned in the past
It made me 
"saved my studies"
How I did it: I Re-did a test voluntarily which I had passed officially without having actually taken it. When a friend had to do it I seized the chance and completed it with him.
Lessons & tips: Learn with a friend.
Resources: A friend and a few good books.
