I think you have to be smart about selling on Craigslist. You should never put your address or home phone in the announcement. An e-mail address or a cell phone is okay. If you live alone and are nervous about having a stranger come to your home then call a friend to come over before the potential buyer comes to see the sewing machine.
Some items sold on Craiglist you can easily take to a public place to show but other items that are heavy or awkward need to be left at home.
I would make sure that when the potential buyer comes to your home that if you have really expensive valuables that they are put away temporarily.
If it's cash being exchanged make a receipt for the buyer and be sure to state. the date, the dollar amount, the item sold, who it was sold to and 'sold as is' on the receipt. I would not take a personal check I would take a money order or cashiers check.
I think most people buying stuff on Craigslist are honest and not criminal but you always need to be wary just in case. Good luck on selling your machine.