Investing with long term trends ( long trends measured in "years" ( in the U.S. markets) have statistically high persistence ). If you want to attain "alpha" vs. the S&P500, invest in stock universes that have been proven to produce highest decile alpha premium via empirical research over decades. These universes include: small cap value, mid cap growth, shareholder yield. These can be attained through low expense equity based products ( ETFs).
A simple, low transaction, and empirically tested way to reduce risk and compound assets has been to use a price vs. 10 period monthly moving average of the S&P500 crossover strategy ( investing in equities when price > MA and money market when < MA ). Further alpha can be produced when a long dated bond fund is implemented ( when S&P500 price < MA ( money market ) and bond proxy > MA, then invest in bonds, if not then cash ).
Decent risk adjusted alpha has been produced with the use of the "mid cap growth" Powershares Nasdaq 100 ETF ( QQQ ) as the proxy for equities within this strategy over a 30 year period ( 14.2% CAGR 1986 - 2015, 13.7% CAGR since 2002 - 2015, 15.5% 2008 - 2015. Of course, past performance is no guarantee....