Just been reading through this thread and interesting points coming out.
Here is my take.
I have found that there are 2 qualities that make somebody a success above all else and these are Discipline and Patience. If you have these qualities then you can use a variety of methods to take your signals and still make a success of it. An example of this is somebody who uses things like moon phase and still manage a +ve PnL.
It takes time to develop a "system" but you do need one, no matter how simple, and once you have it you better stick to it. A "system" does evolve over time but ideally it will remain as boring and easy to execute as possible.
Generating Long/Short signals is only one part of the system and often books pay far too much attention to this or that so called "winning" indicator. The entry signal is nothing if you do not employ a rigorous risk management system. The risk management is the real key and this of course is where the discipline really counts.
I spent so many hours backtesting tradityional indicators that it doesn't bear thinking about. My conclusions are the same as others in this thread. They do not work in the textbook sense. Anybody who has dabbled with Tradestations backtesting will tell you this. If I look at a chart these days I pay far more attention to price action than what any indicator might suggest. Actually now I only look at a slow stochastic and a single MA but pay a lot more attention to what the price is suggesting as it is the real product of buyers and sellers are thinking.
Never think you are right to run a stop because the market will bite you and if you get away with it once then the next loss will likely be far worse.
Paper trading can only get you so far. You will never know how you will trade with real money until you get stuck in.
Trade smaller than you think you should and do not trade with money you simply cannot afford to lose. There is a big difference between trading and punting. Every successful trader fully understands that.
Be proactive. If you can turn an in the money outright position into a better risk by employing a spread or options, do it.
Do not rely on only technical analysis or only fundamental analysis until you find what best suits you. Fundamentals are great in the commodities to provide a long term view and technicals are great for timing your entry and exits.
Never take boredom trades, these are punts and will net lose you money. Wait for the market to show you a trade, do not force yourself to find a trade in the market.
There are a lot of these "rules to live by" that I have discovered either from others or the hard way.
Good trading