The main rule of the market is that noone is your friend. They all try to transfer your wealth to themselves and vice versa. Your main purpose is to increase your wealth, by winning profits from others. Never forget this.
Secondly, the market consists of bull and bear cycles. Someone who got rich during the bull market and touted as legendary could become poor very easily when it is the bear market. So, be prepared to trade both sides of the charts or find yourself an indicator that will tell you when to trade and when to sit on the bench.
Personally, these two are the most important aspects of trading. If you want to learn more about the basics and some simple indicators, you can Google "Alexander Elder - the new trading for a living", a psychologist turned trader. I'm pretty sure pdf of the book is out there somewhere.