I’m not a big fan of top 10 lists, but I highly recommend reading Meir Statman’s top 10 list of errors average investors make. Statman hits the ball out of the park. I can see my own tendencies in every one of the errors. I might go so far as to say that investors should reread this list just before making any trades.
Even easier than seeing your own errors is seeing these mistakes in other people’s behaviour. However, I try to avoid pointing them out to all but my closest friends and family. Few will thank you for criticism and only those closest to you will forgive you and maybe even thank you (much later).