I learnt a lot about what are not the secrets to trading the hard way over six years of buy and hold investing and then two years of failed day trading. It's a lesson that cost me about £40K to learn. Fortunately I didn't do what many others did and give up (although I felt like it sometimes!) and I've pulled through and earnt my £40K (and more) back over the last two years or so.
I'm now of the opinion that one could virtually stick pins in the FT to pick stocks and make a profit if discipline was applied to the money management aspect of it. Of course, one can improve the odds a bit by applying at least some common sense to the entry parameters.
But I'm still learning. I'm not a big investor by any means and I don't rate myself as hugely successful, but I have made a lot of progress over the last few years and am now trading profitably.
The most important lesson I've learnt over the last 10 years has nothing to do with how to pick stocks or whether to use trends, RSIs, MACDs, breakouts, swings or whatever - they all work if they're applied with a bit of common sense. The most important lesson I've learnt is to be robotically mechanical about trading, disciplined about money management and to leave my emotions behind when I'm trading.