Demo trading is a good experience for someone who really wants to become a professional trader, but the earlier a newbie in trading forex jumps into real and live trades, the better for hands-on experience.
I did not have the opportunity to learn through demo trading at first, and I consider it excellent. I lost a lot of money, almost all of my capital, but those lessons were well learnt. I also learnt how to control emotions while trading which is relatively absent when you know you can afford to lose the money you are trading with in demo trades.
To learn properly later, I had to stick to practicing various strategies with a small amount of money, trading consistently on a lower time frame, and sometimes going for higher time frames for longer trades I also avoid using leverage, or I use one that is as low as possible. The key should be to find a strategy that gives you more gains than loss.