Let me offer another approach that may have a chance for higher returns than an index fund that most are mentioning here, but of course there is more risk.
There are 10 sectors in the stock market. Buy 1 or 2 high dividend paying blue chip companies with growth from each sector (for diversification), and re-invest the dividends, letting the power of compounding take over for 20-30 years. Make sure you stick it in a tax-sheltered account like a Roth IRA so that you don't pay taxes on all those dividends every year. Here's an example portfolio:
Energy: Exxon / Chevron
Materials: Bemis
Financials: JP Morgan / Wells Fargo
Industrials: General Electric / Lockheed Martin
Technology: Microsoft / Intel / Qualcomm
Consumer Staples: Altria / Proctor & Gamble
Consumer Discretionary: Coach / Target / Delta
Telecom: ATT / Verizon
Utilities: Dominion Resources / American Electric
Healthcare: Johnson & Johnson / AbbVie / Pfizer
The Dividend Aristocrats is also a good place to look for stocks since these companies have raised their dividend yearly for the last 25 years.
http://www.dividend.com/dividend-stocks/25-year-dividend-increasing-stocks.php
Of course you will have to monitor for disruptive secular trends, but usually these stable companies find ways to
adapt. Of course Amazon is the biggest disruptor right now.
This is my approach. My 401k is invested in an S&P index fund, and my Roth is into these individual stocks. I also have a brokerage through Etrade where 10% of my portfolio is trying to hit homeruns with commodities and hedging with gold miners.
Hope that gives another perspective.