A very good lesson from cryptoarket is that, do not make decesions quickly that mighy lead you to bankcruptcy. If you going to invest do some research thoroughly, know the coin if you find it good invest it without fear.
Personally one of the lessons I learnt about cryptomarket is that its a long term investment I never regard it as a short term investment and always take some profits at the appropriate period when the price reached high and avoid greediness, another lesson is that whenever the price dumps it is the most appropriate period to buy, accumulate and hodl obviously the price will recover and pump this had been the case with bitcoin on several occasions as you rightly said fears and emotions had been a major factor in decision making when it comes to cryptomarkets.