Investors are detailed generalists, who know themselves and have high integrity

The detailed generalist:  It is necessary to maintain a reasonably good knowledge of a wide range of industries and businesses.  This helps to get up to speed on a firm or sector within a few hours, permitting a rapid build-up to expert knowledge as the need arises.
It also helps provide perspective on companies and industries you are already committed to.
I try to improve my general knowledge every day by reading the Financial Times, the Economist and by analysing companies.
Know yourself
Know your strengths and weaknesses, and compensate for them.
Given your limitations and talents you should choose an investment style that suits. I have chosen to be a value investor.
I would be useless as a growth investor because I lack the skills to estimate where Tesla or The Hut Group will be in five years from now. But I can look at proven earnings, proven strategies and make judgement on the likelihood of continuation or restoration. I can look at assets and make a judgement on the likelihood of 
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