As the saying goes, everyone starts somewhere. I've had a lot of first time Airbnb users turn out to be excellent guests.
The best thing you can do is communicate. Send them a message and ask for a little more information. Something along the lines of "Hi XXX, thank you so much for choosing our accommodation for your first Airbnb experience. As a host I like to learn a little more about my guests before their stay, can you please tell me a bit about you, what brings you to the area and who will be joining you on your trip." Most legitimate guest will be happy to provide those details. Through that process you can gain a better feel for them and decide whether you are comfortable.
For me personally, I also require gusts who book any of my properties to have a legitimate photo on file, and have their identity verified. If they are missing one or both of these things, I send them a prompt in my "thank you for booking" message and ask them to kindly provide those items.
At the end of the day if you are not feeling comfortable with a booking contact airbnb and have them assist you in cancelling it penalty free.
