It takes a level of expertise before we can actually call ourselves a successful traders. There are many tests that we need to pass before this can be ascertained. But no matter how expert we may be, there may still may be some days that we will lose. Expert only minimize lose, they can't prevent lose. Losing is a part and parcel of forex and even most trading.
What makes a successful trader? A successful trader is not born in a day. In fact, he's a product of many loses and loses. The more we lose, the more we are clsoer to bsing an expert in the game of trading. So a successful trader is the one that is not scared to lose his money.
Other thing that a successful trader needs to do is to make sure he doesn't trade unless he has the right signal. He may be the one that will be doing the analyses and some times, he may be based on the opinions of others. But I don't always suggest copy trading for a successful trades.
A successful trader must the essence of right time. There is right time to enter and exit a trade.