First you can use backtesting. Here you take your system and figure out on paper how well it would have done on the recent historical market, i.e. The last half a year or whatever period you choose. This doesn’t take too much time because you can rapidly scroll through historical charts looking for the signals that would have led you to make a trade if you had been operating your system live at that point.

Backtesting should give you an idea of whether a system has potential. Of course the market isn’t going to repeat in precisely the same way so you do need to take into consideration the indisputable fact that you could have struck fortunate or unfortunate and picked a point when the system performed surprisingly well or badly.

For this reason, it’s best to backtest over the longest possible time and maybe split your tests so that rather than testing, for example, one whole year when the market might have been especially powerful or feeble, take the first quarter of year 1, the second quarter of year two, etc so you test one 3-month period from each year of 4 years. This gives you a good period spread without requiring you to cover 4 entire years. Here you are dealing with the live market but not using real money. This technique is slower because you have to wait for your signals to come up for real . On the other hand, it mimics real live trading methods with the chance of slippage and other things which are not gong to show up in back testing. Or you can use several demo accounts. Most foreign exchange brokers will supply free demo accounts which you can use to test currency exchange systems.