Meet at a public place. Yes, anyone can get your address, either off the Internet or from a title, but why tempt them. Keep the honest people honest
I would concealed carry, but that's me and something I would be doing anyway.
If you go by yourself, make sure you tell someone where you are going / what you are doing and check in with them when you get back.
You could do the old "dial 9-1-1" and be ready to press call/send if there's an issue, but I think that's a bit of overkill.
Another option might be to have a bluetooth headset on and have someone on the phone wit you while you complete the transaction.
The problem with those ideas is that if something does go south, you have no immediate help.
This is slightly different, but I have a friend who is downsizing his gun collection through a local online classified that allows firearms listings (obviously not craigslist). He chooses to open carry during these transactions, but I personally don't think that's a great idea (as has been said already, I think it's asking for trouble - although not as much as announcing he'll be packing when setting up the meeting). I often ride with him (he doesn't disclose this) and more often than not, the person he's meeting has someone with them as well (generally they don't disclose this either). We assume they will bring a "friend", and I always assume they're armed. There's a sort of understanding to these transactions.