Vanguard Founder John Bogle developed a very simple yet successful investment strategy which includes using low cost index funds, investing rather than speculating, investing early and often, diversifying, minimizing taxes by maximizing pre-tax savings options (e.g. 401K, 529, 403b, 457b, traditional IRA), and to not try to time the market.  People who follow this strategy are generally very satisfied and often turn into firm believers known as the Bogleheads.