trading is one of those things that you have to spend a lot of time learning it. people keep saying "buy low sell high" like a chant but they don't understand it and that's the problem. it is very easy to learn too but it takes time. you have to start hanging around in the market (on exchange) and start staring at the charts for a long time and try to analyze what is happening in the market.
and also you should always know that the markets are different from each other.
If you lose lot of money try again . In investing loss is normal. I think we'll get better and better in trading if we know how, and know what to avoid to do, and what's the best we should do. Don't just complain because of the loss and give up, but keep trying until we can earn more than we loss. Learn how to invest properly to avoid loosing