Well I bought in at 16.10 and just sold at 13.00 after mtgox kept going down, now the price is very unstable got to 12.50 now it's at 13.00
You only lose money trading if you sell lower than you buy. The only exception to this is if a company goes bankrupt or the price never recovers. This goes for any market.
If the price drops below what you bought it for, just WAIT.
That sounds great and all, but it doesn't really make sense. The price may never come back up, in which case he would lose far more by not selling now. Taking a small loss is better than losing everything.
Of course in this case prices will more than likely be back up in a few days, but that's another topic.