Hi James,
from my own failures I learned that - specially if you are not a veteran - it's the best way to trade with the trend.
On that day we were in a minor uptrend and because of that maybe a short would not be the best choice.
Of course this is very subjective and I have no idea how you trade. I for myself stopped trading live at the moment, I paper trade only.
The main reason why i reply to your post is that I recently found a thread which could be helpfull. For me it was a good read.
http://www.elitetrader.com/vb/showth...olume+analysis
All the best