What is your occupation? Find some companies in your occupation area and get their annual reports and 10-K's. I like to get the printed copy of the annual reports as they give you an impression of how frugal the companies are.
If you can find them get ahold of some of the early Berksire reports, the letters are available on the BRK site, but it helps to have the reports to read and see what he is talking about.
ditto WSC
I would also suggest you read books of other types of investing, just so you know what others are thinking. I agree that smaller companies are better and easier to understand.
Google "annual reports" and order all of an industry you are interested in.
https://www.orderannualreports.com/sector/Default.asp?mkt_code=GOOGN20203&s_kwcid=TC|13088|annual%20reports||S||5307958450 is a place to start.