There are many strategies in FX market among them few are as below (with or without indicators).
Martingale.
As we know any EA which use martingale logic eventually one day account will get wipe out, since we don't know where the market will go and when.
as the market will move againist to us we used to increase the volume size this put pressure on account balance and margin.
hedging
when we compare to Martingale, hedging is some how good. but here the problem is when to hedge and which pair. after hedging how to break it with profit ? it again required to place multiple lots by following with grid specified distance or with out grid . multiple lots may/may not with or with out incremental/multiplier. again the question is to which pair? Ranging or Trend currency pair? this logic also risky.
scalping
in my view it is better to think or talk about scalping as little as possible even forgetting is the best way. any scalping ea logic require very low latency, small or negligible slippage , fast execution of trades at broker server. for example if our scalping ea tell to place buy lot at 0.12345 , at the time of placing order price will move to 0.12300 . our ea logic is perfectly correct but no scalper ea will place with pin point accuracy of price target. if our scalping ea place the order it take some time to reach broker server then broker will acknowledge with requested trade and place in out trading account . all this process will take some milliseconds of time gap. in this gap our target price move to some where which is not at all our ea target. again in this commission also need to calculate in profit. so in practical, with live/real accounts it is very difficult to get success with scalping logic.
Arbitrage
as the name suggests, the logic involves comparing the prices of different sources (usually brokers) and place the trades. it requires opening the account with some third party , they will provide the data feed into our trading terminal, in our terminal arbitrage ea will place orders. some brokers restrict this kind of trading . I am not much familiar with this kind of trading to be honest. in order to not known to broker about arbitration process, in recent days traders are looking for hidden arbitration ea.
Grid
trading with grid specified gaps may get good profits. but which pair? if we feel one pair is trending today tomorrow it behaves as ranging. so this also involves big risk.
My attempt:
I traded with live accounts with hedging,scalping,margingale, grid. I don't have any experience with arbitrage. with my experience with all these strategies, I constructed an EA with below specifics.
1. my ea is not scalping or arbitrage.
2. this ea place orders using indicator (buy/sell)
3. after placing the order,in most of the cases, it place opposite order . but this will not place immediately . it place the order on indicator signal and gap bet ween previous trade. (hedging)
4. if price move againist to any pair even after hedging, then it place martingale incremental lot with indicator signal only.
the above logic may /may not work in all pairs. so that I dicided to trade with all pairs except some GBP* pairs. by using this logic, if this strategy work in some pairs, and fail in some other pairs, on average with basket profit , we are exiting from all trades with 3 percent of profit of opening balance of account. like this we are trading 2 times 6% profit we stop trading for that day.
precisely it uses martingale but not all pairs not in all conditions. it uses grid and hedging but not in all pairs and not in all conditions.
so this ea is martingale+heding+grid+indicator ea