Not to brag, but I rock at selling stuff on Craig's List. I often sell things for close to what I paid for them. A few friends can vouch for my Craig's List skills.
Anyway, it's easy to sell stuff to rock at Craig's List. Here's a few things to think about.
List stuff for a bit higher than what you want to get for it. People always offer lower than the listed price. This gives you room to go down the price you actually want.
Be firm with what you're willing to accept. People will usually respect that.
People usually email asking if the item is available. When you reply, say that is (if it is of course) and ask when they want to meet. Making the transaction as soon as possible is key. Waiting gives them time to change their mind, find something cheaper, or whatever else.
If there are other people interested, I always mention that. People knowing that other people might get it before they can makes them move faster. I've had people cancel dinner plans and come meet me to buy something because they didn't want to lose the chance to buy the item.
Only accept cash. If anyone won't pay with cash, they are trying to scam you. (While we're on scamming, if anyone ever offers to pay more than what you're asking, that is definitely a scam.)
People love stuff in the original box and when you say what cables are included and such.
Good photos are a must.
Keep descriptions short and to the point. People rarely read them anyway.
I'm sure there's more stuff, but that's a good start. Once I started selling stuff on Craig's List, I got hooked. It's an awesome feeling selling crap you don't need and getting cash. I paid the downpayment on my last car with all cash from Craig's List sales. Pretty cool.
By the way, one of my friends has a great app for browsing Craig's List on the App Store.