For some investors, only the long-term matters in their buy and sell discipline, and therefore they should only heed my comments regarding the longer-term time frames. For other investors and traders that have a more short-term orientation, they may want to ignore the longer-term outlook and focus on what I say about the shorter-term picture. Either way, whether you are a long-term investor or a short-term trader, you need to have a pre-established system in place for buying and selling. If you are a long-term investor and you are currently thinking about selling because you are nervous about stocks being at all-time highs, then stop! Being nervous about all-time highs is not a sound reason to sell stocks. Similarly, if you are an investor or trader that is nervously watching the market make all-time highs and you feel anxious to buy because you do not want to be "left behind," then stop! All-time highs and/or a fear of being left behind is not a sound reason to buy stocks. Take a step back, take a deep breath, get a system, and stick to it. In the near future, I will be writing about my own systems that you can consider adopting. -- Written by James Kostohryz.Follow @jameskostohryz This article was written by an independent contributor, separate from TheStreet's regular news coverage.