As Warren Buffett has quoted, Rule #1: Don't lose money. Rule #2: Don't forget rule #1. What this means is, when you buy an On Sale stock and it goes down lower than your Buy price, you do not sell. On Sale stocks have proven to have strong financials and eventually those stocks will go back up. This is the discipline of not worrying and letting great businesses make you money over the long term. Most novice investors lose money because they sell when stocks are down.