Don't sell on bad news.
When it comes to investing, my suggestion is to first understand your strengths and weaknesses, and then devise a simple strategy so that you can sleep at night!
You have to have patience in this field.
Basically, we try to buy value expressed in the differential between its price and what we think its worth.
Sell is tough. It's the worst, it's the most difficult thing of all.
We like to buy stocks which we feel are undervalued and then we have to have the guts to buy more when they go down.