It's easy, before every trade you decide where to put your stop loss, and where your profit target is (even if it's a trailing stop, or a MA stop or something else, doesn't matter). Then you enter the trade and sit on your hands.

It either works and you make money or you make a small loss. Don't 'fiddle' with the trade, you made a decision at the start based upon the available evidence, and until the trade either wins or loses, it's still the same evidence. There shouldn't be any reason to change the trade plan halfway unless it's due to fear or greed, and in both cases you'll end up losing money because thats gambling, not trading.

I'm not saying you shouldn't move stops up to breakeven, or lock in profits, but only if you have some rule set in advance and you follow it to the letter.

If, over a period of time you find that you're losing too much money to not making enough, then go back and re-evaluate your system, but you need a set of rules on every trade that you never deviate from.