AT T GRANTS NEW MEXICO
You should never place an exit order before you know that your entry order is filled. When you trade open outcry markets (non-electronic) you might have to wait a while before you receive your fill. By that time, the market might have already turned and your profitable trade has turned into a loss! When trading electronic markets you receive your fills in less than one second and can immediately place your exit orders. Trading liquid markets you can avoid slippage, which will save you hundreds or even thousands of dollars.
Principle #3: Realistic expectations.