I followed this advice as closely as possible with the means at my disposal - and it helped (I do not know enough to short stocks yet - so I am only making trades to catch a bounce up)
--- these are good points:
--Determine a trend in BOTH the stock AND the market, and trade only in that direction. This isn't rocket science. Use an EMA of a decent length, and eyeball the charts of the stock and the S&P.
--Buy into a stock's weakness in an uptrend, and sell strength in a downtrend. In an uptrend, you will be looking for a sharp selloff as a good entry point as that is most likely to attract buyers. Imagine yourself owning the stock. Would you be throwing up at this point and selling in a panic? Good. It's time to buy. And in a downtrend, look for sharp rally that you can short. Over the past 90 days, there have been clear periods of strong market and stock uptrends, and downtrends. September, a great month to be buying weakness. October-November, an excellent time to be shorting any sign of strength. A super trading environment. The best in years. If the overall market is not in a clear uptrend or downtrend, then tread carefully and trade very small.