Discipline, discipline, discipline. Easy to hear, hard to do. Let your winners run and chop your losses strangely, most do the opposite. OK, in the long haul, stocks may recover to a former high, but meanwhile, your trading blood, Capital, is tied up in a loser. Had you simply taken the loss early, you could get on with more profitable trades immediately not to mention the stress relief.
Trading is simple merchandising.
If you want to be a good merchant, you must buy reasonable inventory at a good price and then turn it over, hopefully, for a profit but turn it over that is how profits and cash-flow are generated. I have smelled old mackerel. Under this same heading, we have to look at our analysis. You cannot afford to become emotionally attached to your stocks. These are inanimate things, and it is probably immoral to become married to them.