The thing is, in stock trading, just as in poker, you're not supposed to get emotional. In poker, you don't want to have a "tell" so that other players can read you and realize that you're bluffing, or realize that you just flopped the best hand possible. Your goal is to sucker the other players into either folding against your weak hand or betting against your unbeatable hand.
In stock trading, getting emotional means allowing paper losses to entice you to sell for a loss. Or even losses in one stock leading to the compulsion to trim holdings across the board, forgetting why you invested in a completely different stock in the first place.
See, I got a tip that Taser International (TASR) was going to be receiving orders from the new French government for Taser weapons for all their police personnel. So on a whim, on 5/3, I bought 10 LXFAB (Jan 08, $10 options), for $900. The stock gained a little and I continued to hold. Then on 5/9, Dendreon tanked, and I was looking at losses instead of the huge gains I thought I was going to realize when Provenge was approved. So I trimmed my Dendreon holdings (after failing to take reasonable profits earlier, dollar signs in my eyes), for an overall loss.
I thought about trimming other things at the same time. I sold LXFAB for $1250 ($1.25 per) and I sold ELNEC (May Elan $15 call) for a small loss. Now, if I'd held ELNEC through 5/11, I would have seen great profits (200%), and LXFAB was recently selling for $3.20.
So I'm not a very good stock trader. I get lucky at times. I let my emotions rule me. I don't take profits off the table when I should, I sell too early for marginal gains, I let bad news in one stock bleed over to my feelings in other stocks, I get emotionally "married" to stocks, where selling some is in a way a betrayal, and I don't accept small losses ... I hold on, and they soon turn into big losses.