Markets Aren’t Efficient
Relative Performance is a Dangerous Game
This Time is Never Different
Valuation Matters (in the Long Run)
Wait for the “Fat” Pitch
Leverage Can’t Turn a Bad Investment Good
Beware of Over Quantification
There is No Substitute for Skepticism
The Benefits of Cheap Insurance
Some of these are probably more useful to you than some others.
Markets Aren't Efficient is a good one. I would tweak it to say that markets are efficient except for when they aren't. I recently read something that said people rely on markets to be rational (perhaps a synonym for efficient) when they themselves are irrational. Markets do tend to be rational most of the time but occasionally they go off the rails which can lead to great upside like 1998 and 1999 and sometimes it can go the other way like in 2008 when some stocks went to single digits when there was no justification to go that low (some stocks were justified in going that low).
This Time Is Never Different is useful too. Many people really thought the financial world was ending, there was genuine fear that the Great Depression was back and so on. Amusingly I was "too bearish" and then I wasn't "bearish enough." A point I tried to make repeatedly is that while the details were unique the human failings behind the details were not. People are (collectively) greedy, they misuse leverage, don't appreciate the risk they take and often react by selling low. You saw this ten years ago and you will see it again, guaranteed.
What sticks out for you?