Another piece of advice to add to the sage wisdom offered above: paper trade. That means setting up an "account" that doesn't really exist, and trading as if you were actually using real money. Do it exactly as if you were risking your money. Once you're feeling comfortable, open a small account (if you decide to continue) that you can afford to lose completely.
I paper traded commodities and options for three years before trading a $10,000 account for another three years.
In the end, I broke even, which my broker said was good. But I was spending a lot of time trading, and not making much, nor losing much. My broker said that I was being too conservative.
It was a good learning experience, though, and if I didn't have a "real" job that required my time, I would have continued.
I know people who do very well at this, and I know people who've lost everything they own.