The only way to double my money that I have really tested and I have realized that actually can generate high yields with relative low risks is the forex trading, especially following a strict money management and a proper strategy.
Forex trading is good but should be used with care so you dont lose your money
Forex trading is not easy as normal trading sites ,there is you need a fast connection and also a good predicting skills i think .i have a friend and he says forex has a big difference in common trading sites .forex gives a high profit but also it have a big risk to try on.