I think everyone should develope his/her own 交易系统 （看均线大哥下面的帖子）。There isn't a perfect one, but you have to make one that you feel comfortable so you can stick to it. This way, you are less likely to be taken over by emtion.
Some of my principals
1: Have an asset allocation ratio. This can be anything but you need to stick to it. For example, I would try not to let the total value of individual stocks to be greater than 30% of my portfolio. If a individual stock goes up too high too fast, sell some of it and convert that money into QQQ or SPY
2: Only invest in the aboslute leader in a particular sector. Until fundamental changes, try to stick with this stock for as long as you could. The fudamental change could be that this company is no longer a leader, or that sector is not likely to grow. Otherwise, try not to sell unless I have to rebalance for the reason #1
3: Trust US and US economy. Just can't think of another country has better long term prospect than US. If you dont believe in this fundamental, well, you should not touch stock market at all
4: It is ok to trade the rest of stocks for fun or to make some quick money for a nice vacation trip, but only with a very small portion of the portfolio
5: These are fundamental principals, when it comes down to actual exeuction, I use options a lot to hedge. For example, I did not sell any of the major porfolio in late July but did rely on options heavily as protection. Of course, this has downside too as you could end up completely wasting those premium. But I have found that it helps me to control my emotion at the cost of a small premium, and over the long time, I can hold some of the best stocks for a really long time
