As with any of these online booking sites (Homeaway, Clickstay.com etc) you should make sure you have contact with the owner, just to get a sense of how responsive / helpful they are. You might also contact the customer services and ask if the owner has had previous bookings (and did they go well, have they responded quickly to other holiday-makers etc). I personally would prefer to only book places that have got legitimate reviews already. Definitely don't do a bank transfer to the owner (if he or she even asks you to, I'd be worried), and check how your money is protected by Airbnb - search for "renter protection policy" or similar.
I'm sure it will be fine but doing these simple things will help make sure 