I've found that with Craigslist you have a greater chance of being contacted by flaky people / idiots when the items you are selling have a broad appeal, or require no special knowledge to purchase or use. Set a firm price, state how you want to be contacted (email, phone, etc.), and state that you want serious inquiries only. I usually prefer email because I don't want to give my cell phone number to any of the freaks and weirdos on Craigslist.
For example, I sold a TV on Craigslist about a year ago... I was asking $200; thinking I might get around $150 for it. My inbox was suddenly flooded with emails consisting of little more than "u hav tv?" or people offering me half of my asking price or less. After talking to some of these people (big mistake) I relisted it with a firm asking price of $150 and decided to sell it to the first person who could send me an email containing a complete sentence. I sold it for my asking price within 24 hours.
On the other hand, I sold two camera lenses for a DSLR on Craigslist at the same time and had none of these problems... but of course purchasing a camera lens generally means that the purchaser is at least smart enough to operate a fancy camera.