For layman like me, diversification is best strategy.
Deep research and analysis is really a skill. Stock picking and being successful is tough.
You see I only start to get active in stock investment when I am near to age 55 for which I don't want to work anymore. So now in advance I learn a bit on stock picking. Actually if you are not a trader you don't need to do very in-depth chart analysis etc either. I pick stock based on my everyday interaction with the stock products and services. E.g in my line of work MSFT is everywhere even more so in govt civil service. Same for GOOGL, AMZN for their cloud services etc. AAPL for their products. You can't go wrong with these giants but of cuz we all know giants of today can become dwarf of tomorrow and that is why never all in on any investment instruments.
For layman, either choose ETF, mutual fund which is a basket of stocks will do. There are contra,cfd,options,forex etc much more riskier investment instruments for which I don't touch just read about them. Coupled these with bank FD, T-bill, SSB, endowment insurance, high yield savings account (no need play game that kind), money market funds, REIT etc and I think should be pretty ok.