Technical Analysis
Ok, here are a few things to look out for when entering or exiting a trade.
First is this IPO, (initial public offering, couldn't find this pattern in AAPL off hand) which shows a gradual slowing down of the downward trend, or a good indication of an upward trend.
And of course the dead cat bounce, or an initial upward spike after a plunge. This usually indicates more of the same or a much bigger plunge, (one to keep an eye out for).
Dead Cat Bounce up close.
And the reverse is also true, eventhough less likely to increase substantially over its opposite.