Taking profit early can ruin the trade.
Rule: Take profit more than 1:1 risk reward on every trade.
Taking profit in the correct location is as important as the stop out location and the trade itself. Taking a profit early that changes the risk reward to less than 1 to 1 makes the trading system a losing system. You should get at least a 1:1 risk reward and more to have a profitable system.
The two options are winning more than 50% of your trades or taking profits more than 1:1 risk reward.
Taking only 50% to 80% of the share size as profit at 1:1 and allowing the rest to continue is great if the trade works. However, when it pulls back after the 1:1 profit taking and stops you out, you just had a trade that's less than a 1:1 risk reward ratio.
Like with most things in life I find that a combination of both works best. Watching closely to let the stock run as much as possible before taking any profit, and then letting the remainder share size work with a technical stop at the 1:1 area, or at least closer than the entry if possible.
One other method I use is ASAP STOP, to limit the losses as soon as possible. As soon as the stock makes a good move, place the stop at even, if the trade starts to fail before 1:1 take 1/2 profit and leave the remainder at stop out even or a closer technical stop. This method works great but I will usually end up with more smaller winning trades because I will miss some big trades that first pulled back to my entry before they took off.