Never lose money

The temptation of selling on loss when you discover another opportunity with a perfect timing "now" is really tough. I still remember a moment when I invested some capital in a company A, when after a couple of months the value dropped by a good 20%. At that time a very interesting crypto project popped out that attracted my attention. And I really wanted to sell on loss of 20% to get potentially positive 50% or more. But in reality selling for loss is not always the best idea. It is quite often when trying to cover the loss by investing somewhere else, the loss only increases.

Never sell on loss unless you are 100% sure that your next investment target can cover it.

Patience is a key. If your stock doesn't recover at all - well, you initially made a mistake by investing there. However if it is just a monthly/yearly spike of price or some temporary event that affects the price - just wait.