One rule I set for myself when purchasing domains was to stay away from anything other than .com names. It just makes sense to me. If I were starting a business (which I have), I would want my company site to end in .com.
I already broke this rule. Yesterday I purchased ChristmasMorning.net. Not that I think this will be bought by someone looking to name their company after it, but because it sounded like a good name for a shopping site or some other Christmas related site. Needless to say that the .com was already registered. This is maybe one of two .net names I own and I really don't plan on purchasing others until I learn a bit more about successful domaining.
I also need to stop going on gut reaction and apply some of the domaining advise from those experienced in the field. Is ChristmasMorning.net a good name? Not sure. It's currently parked on WhyPark.com with most of my other domains. I put a sale price of $900. I'll post any progress I make with this site as far as an actual sale or if I choose to try to develop it.