Stop loss plays a vital role for saving a trade. How much pips away do you set stop loss?
1. Learn Price TA so that you know where "support" and "resistance" are on the chart.
2. Most logical place for a stop is just below support or just above resistance. Those levels are SUPPOSED to hold if tested... by definition
3. The size of your stop should be determined by "how close to support/resistance" you got your position. If you were a bit late with your play (that is, if support/resistance is further away from your trade), you need a larger stop to be technically sensible/correct.
Of course, you can always use an "arbitrary stop"... like 2 points or 50 pips. Those can also work when the market goes IMMEDIATELY in your direction with little or no "back flushing".