Depending on the individual trader to determine to stop loss. You should set your stop loss in accordance with your TP. If your SL is 100 pips, then your TP is supposed to be 200 pips. So far I try to make my stop loss around 20 to 50 pips. What I experience is if too small stop loss, mostly price always hit my stop loss. So I try to wider the stop loss and use a smaller lot size so I can enter a few times. So far still try to adapt to this stop loss level.