The most recent annual report – While reading the annual report, you'll want to pay special attention to the letter from the Chairman, CEO, and sometimes CFO or other high-ranking officers to see how they view the business. Not all annual reports are created equally. Generally, the best in the business is considered to be the one written by Warren Buffett at Berkshire Hathaway, which you can download from free on the holding company's corporate site.
IMPORTANT – Like paid subscriptions, be careful with classes and courses. Most are easily over $1,000 and are sold with false promises to acquiring valuable knowledge. Their fantastic sales funnels will suck you in, take your money, excite you during the course, then leave you with a strategy that wasn’t even profitable to begin with. See, 10 Things I Wish I Knew About Trading Before I Got Started.