Alexander Elder explains the importance of the 3 Ms i.e. Mind, Method, and Money. Which basically put means you need to master yourself first i.e. have discipline, avoid making the natural/common psychological mistakes that most people are wired to make. Only then should you focus on putting together a winning method which suits your style and circumstances and of course makes money. Finally the point of money is about having adequate risk management policies and procedures so that you don't blowout as a result of one or two mistakes. Well worth a watch for those considering or already trading for a living.
The videos are pretty poor quality but the information and insight into successful trading is priceless.