If the futures are in an uptrend, but your stock is moving down this could signal a possible explosive move down when the futures start to go back down again. The same applies in reverse for moves up.

If trading NASDAQ stocks, be aware of what the futures are doing. The current March contract symbol for the Nasdaq Emini 100 futures is NQH08 / NQH8 depending on your broker. Stocks usually move with the futures. It is generally a bad idea to short a stock if the futures are in a strong uptrend, and vice versa for going long.