Gary,
But with the best will in the world, you don't know what you are doing, you only think you do. You have no idea what to look out for, what to avoid, what not to do, or do in certain situations and that is like playing Russian roulette with both your reputation and your wallet. And for all you say it's simply about common sense, it's not, the simple things are, but the things that could cost you money are not. But perhaps you have to learn that lesson all by yourself. If you were a professional at heart you would set aside your arrogance and do the training - you never know, you might learn something that could make you even better than you think you are - professionals have that level of personal commitment. Question is, are you a professional, or a know it all amateur?
Simon