I am not an attorney (/disclaimer).
I was incorporated as an LLC for trading purposes for three years. I found a better way than the do-it-yourself LLC kit was to hire a tax lawyer to structure a set of entities to save me money. I now pay about half the tax that I did as a member of an LLC.
I don't know what state you're in, so of course I recomend you see a tax attorney, but NOT a CPA or regular attorney. They won't know what you're talking about. If you're serious and your trading business generates sufficient wealth that you want to protect long-term, talk with a $500/hour tax attorney. IMO, anything less is more expensive.