It is pretty normal. A lot of guests that book my rental are new to Airbnb. I probably get more new guests then I do seasoned guests.
My recommendation is collect as much info about their trip/ stay as you can.
For example, I always send out these three questions to guests:
What time can I expect you to arrive?
How many other people will be traveling with you?
Are you here for vacation, family, travel, ECT...?
This will help you get a better idea of who the guest is and why they are booking your place.
Sometimes you can't avoid bad guests, even if they seem like awesome guests and have all their verifications.