The key to any long-term investment strategy is to cut your losers and run your winners. Do you struggle to take a loss on a share which is underperforming and unlikely to recover in the short term? Alternatively, do you sell your good investments too soon?
Unfortunately, many people suffer from this problem, selling their good shares too quickly while holding onto loss-making shares, which is often something of an ego trip. In many ways the hardest thing to do is take a loss but if you continue to hold a loss-making share, which is still falling, this gives you less funds to invest in the future. Keep your eye on the long game.