Haha sorry but no, 20% is waaaaaaaaaaaaaaay too high, that's immensely high. He'd need to stay in the 1-5% of total equity risk per trade. A good strategy that works is staying at a baseline level, of like 3% or 5%. Then, from here you need to make up your own rules. If you get a streak of, let's say, 3-4 losses back to back, you half down the risk per trade to 1.5-2%. If you get ANOTHER streak of loses you half it down again, going to even 0.5%. This is very important as it is actually very likely, depending on your win rate and strategy, to see back-to-back loses. So by minimizing your risk after every streak you can survive and stay in the game. If you have a strategy where you have high risk:reward ratio setups but have a lower win rate, think about it: you only need to have a winning trade out of one of every couple of trades, to be profitable. Never revenge trade and increase risk to make back all that you lost. Rarely you might win, but most likely you'll be filled with emotions, make a bad trade and lose it all. So discipline and a strict trading plan are what will allow you to succeed. Check out Cryptocred's risk management video in the technical analysis series. He explains it VERY well, best basics on risk management explained on YT imo.
Also, the only way you prove what other people say here that go like "Forex=scam or gambling", is when you trade without knowledge, that's it. The first and foremost question you have to honestly ask yourself to see if you're gambling is: Do I have a REASON for entering this trade, a thesis? If not, then you're just gambling your money away, and believe me the market won't give a shit and take your money right away. When you acquire real and practical knowledge, only then can you distinguish gambling from making your money work for you in the foreign exchange market.
About brokers, yes there's scam brokers out there that can fuck you over, manipulate the prices and even not let you withdraw. So do your research and find the most reliable one out there based on where you live. Check every broker's reviews on forexpeacearmy . com.