The appropriate stop loss broadly depends on the type of method, setups and time frame you are using, then the price action unfolding can indicate appropriate exact levels to fine tune it.
I'll use anything from 4 to 25, depending on the setup, time frame and price action. Sometimes up to 50 for overnights.
As a rough rule of thumb I look for about 1:1 and a bit (R:R) so an 8 point stop would be looking for a 10 point profit.
I mainly trade intraday and try to grab 5-40 points here and there, when I'm not making a mockery of my system of course.
you might want to ask TraderTony, tradesmart or Chartman (to name but 3) as they are better qualified.