Ah, yes, the key conundrum: with whom shall I entrust my trading moolah?
Well, most (surviving) brokers are regulated (if you're a cynic, that won't mean much), but, when it comes to conducting due diligence ('Crikey, do you need an anaesthetic...?'), you're looking at Spread, Trading Platform, Leverage, Support (preferably in-house, where you're communicating with people who are empathetic to your account status), and Execution.https://www.flickr.com/photos/111134236@N06/11995339146/
Your're also seeking out Reviews by authentic 3rd parties (for example, reviews of my own broker excel markets), here on myfxbook and forexpeacearmy.
At the end of the day, choosing a broker is not rocket science. Now making money from currency trading, that's another story...
I Think, Therefore I'm Guessing