I buy and sell on craigslist a lot. Here's a few ideas for you that I did.
1. create a simple email address with bogus information on the profile part (if it asks for name, birth date, address etc.) This keeps all the spam out of your actual email account and spammers can't tap into your personal info or stored personal emails. Read the craigslist spam alerts, it'll tell you what to look for. If a reply email says something generic like "I'm interested in the ITEM you have for sale", and not specifically what you have listed for sale, then it's more than likely a scam. Always meet in a public place if you can, if not, have someone else there with you. And only take CASH. Paypal can't help you without a tracking number. Oh and this might seem crude, but if the email has terrible or broken English, let that be a small flag. Not everyone is grammatically correct, all the time, but I'd weed those out personally.