HI!
I have 2 EAs that trade gold in martingale and have excellent results. of course they must be switched on mainly during laterality hours (Asian market).
Also I have a very good indicator from FabryForex which for manual trading is awesome, based on the cyclical bands.
I have seen one in the Metatrader market specific to gold. There's an indicator and an EA for that. You can search for it there. However, it is not free but you can download a trial version and test.