What Investors should NOT do

Don’t get fixated on the price you paid for shares:  What you originally paid for shares is totally irrelevant to your decision on what to do now.  This is especially true if you have to take the decision to cut losses, which may be psychologically difficult.
Undertake fresh analyses regularly, e.g. when annual reports are published.  Look at your revised intrinsic value estimation based on updated information and compare that with current market price.
Is the share now fairly priced or under-priced?
Do not try to guess where the market is heading in the short run
Timing the market – getting in just before a rise and getting out just before a fall  - is incredibly difficult.  There are a handful of occasions during an entire investing career when you might feel strongly about the market’s likely direction. But even then do not put large bets on that view.
Even those with decades of experience great investors conclude that the direction of market over the next few months cannot be forecasted with any consistency.
To try to time th.....