Download Preston's 1 page checklist for finding great stock picks: http://buffettsbooks.com/checklistPreston Pysh is the #1 selling Amazon author of two books on Warren Buffett.The books can be found at the following location:http://www.amazon.com/gp/product/0982...http://www.amazon.com/gp/product/1939...In lesson five, we learned that Warren Buffett has four rules that he uses for investing in stocks.All the rules must be met in order for him to purchase shares of a company.Those four rules are the following:Rule 1: A stock must be stable and understandableRule 2: A Stock must have long term prospectsRule 3: A Stock must be managed by vigilant leadersRule 4: A Stock must be undervaluedWe also learned a very basic valuation technique that Warren Buffett used when he worked for Benjamin Graham.The technique multiplies the P/E ratio by the P/BV ratio and the result needs to be lower than 22.5.A key fundamental of Warren Buffett stock basics is the idea that the stock market is nothing more than a location where he can buy or sell his shares.The market only provides a platform for him to purchase undervalued companies.He always buys on the assumption that they stock market could close tomorrow and not open for five years ?? and it would have no impact on his decision to buy a particular company.Finally, we learned that Warren Buffett possess great patience.He never tries to make enormous gains, but instead consistent gains at reasonable levels.He always thinks for himself and always determines the value of a stock based on what HE thinks a company is worth - not the market.