Recognizing a day that shows itseslf to be hard (for whatever your personal reasons may be) is more than half the battle.
Say to yourself, "this is not my day" and just sit on your hands, and/or leave.
For me, if the Dow, Nas, and S&P are not all trading in the same direction, I will either not trade, or tread very lightly.
If up down volume is not decisive by 10:30 or so, I will not trade. Then again, at 2 pm, if there is not "direction" again (I consider mornings and afternoons pretty much 2 seperate trading sessions) then again, I know it is not my day.
I like to see at least a 5-2 ratio of up/down (or down/up) volume to determine if the market is strong or weak. I like to be ON THE SIDE OF THE MARKET. If I don't know what side is the right side, I am pretty much lost.
As for today, I do not think it has been a good day, but I have seen so many worse. Even very recently.
Last Wednedsday or Thursday, when I was all long and some bullshit rumor about SARS in the Whitehouse made the market plunge, THAT was a nasty event. Fortunately it was early enough in the afternoon to take my losses, lick my wounds, and go back and make it back the next day. Shit like that happens all the time.
Low volume days are just something we have to muddle through. The specialists have their opportunities to screw us all on virtually every trade, but if we know that, it can be avoided.
Not trading is often the very best way to "trade" under certain conditions. It is always better to live to fight another day. Today, it felt good to be flat and have my screen shut down at 3 pm. (Of course, now the market is surging, but you "can't look back". Never kick yourself over "lost opportunities". New opportunities present themselves every day.
Peace,

RS