Whatever portion you may decide to invest in stocks (and I would diversify across a number of asset classes) do not commit more than 5% to any one security and choose those that have consistently paid increasing dividends and paid down debts. Also use trailing stop losses (I use 25%) to limit the loss of capital in a down market. Safety is the watchword, in my view.
Will Rogers, the American humorist, in the depth of the Great Depression said that he was far more interested in maintaining his principle than any interest from a risky investment he might earn, or perhaps lose.