First of all,I think one must have financial stability. Have to take risk of certain amount that won't fall any impact in financial stability.What others thing one must know?
What is your opinion or idea?
I read a lot of books, from big investors like Warren Buffet or Abraham. They are all great books.
But basic things everyone should know are:
Technical Analysis
Fundamental Analysis
Sentiment Analysis
After that you need to get into the market and earn a lot of experience