Whether you are a newbie or a professional trader, forex trading is not a one shot deal. You have to keep learning and improving yourself.
Regarding a profitable system, there is no such thing as profitable system for ever. You have to keep on improving it over time. You can just pick any standard system available for free from the internet and back test it for a year or two using a backtesting software and then, use it in demo and then, live.
But if you have just used a system for 1 month in demo and then, jumped to live, then when it will start loosing you will have no idea what to do next. But sufficient backtesting will give an idea what to expect from the system and when to tweak the system.
Artificial General Intelligence