Perhaps the most important ingredient to being/becoming a good investor...

...patience.

When I look back over the myriad names that I have owned and the reasons I owned them, and then look at when and why I sold them, and look at them now. I would have in virtually 90% of the cases have been much better off holding them than selling them.

The key ingredient that was missing from my investing DNA was patience.

Patience allows the compounding effect of time, the market (generally upward skewed) and your thesis to play out.