Short version: Invest in (1) Total U.S. stock market index, (2) Total world stock market index, excluding the U.S., (3) Total U.S. bond market index. The principles are (1) Asset allocation, (2) Diversification, (3) Rebalancing.
For a lot more info, see (1) "Bogleheads Investing Advice and Info" https://www.bogleheads.org/ and (2) "Bogleheads Wiki" https://www.bogleheads.org/wiki/Main_Page
Here's the thing - you are not going to be be better than the professionals. Whether it's picking stocks or playing poker, you will lose on average.
That doesn't mean "the only winning move is not to play". It means that you need to play a different game. As per Tim Hale's advice - pick a robo-balanced portfolio and don't worry about trying to beat the system.
At small scales, chickens are an incredibly good investment. ~6 months of minor, enjoyable effort gives back years of eggs available for collecting. At larger scales they're probably not so attractive.