To avoid mistakes during bear markets, investors should focus on three key variables: (1) care about the price paid for the business and ensure you get a good price; (2) ensure agreement on the quality of the business, preferring to buy the best business at an affordable price rather than lower-quality businesses at cheaper prices; and (3) only position in companies with strong balance sheets that can withstand shocks, because if you're positioned in the right companies when they sell off, you get excited to buy more