You don't need to be an expert in order to achieve satisfactory investment returns. But if you aren't, you must recognize your limitations and follow a course certain to work reasonably well. Keep things simple and don't swing for the fences.
Warren BuffettThe great personal fortunes in the country weren't built on a portfolio of fifty companies. They were built by someone who identified one wonderful business. With each investment you make, you should have the courage and the conviction to place at least 10% of your net worth in that stock.
Warren Buffett