Well, the first thing is to always trail stop losses in the direction of the trade and not against it. For instance, if you are long, never revise a stop loss lower if in a loss. Only revise it higher if in a profit.
To revise stop losses, you could use indicators such as Parabolic SAR or super trend. We have both of them on FYERS Web.
You could also revise stop losses based on historical supports and resistances.