Craft fairs are hit and miss. They require a lot of research beforehand, lots of work to set up in an attractive way, lots of positive attitude and energy and low expectations. It is possible to sell nothing in one and lots in the next. It's ups and downs. Some say it will be easier if you are well known online first. Then it depends on what you are selling, what types of people will around....
They are definitely worth a try....if they work, they are great. Just go thinking it's just another day at work. You might sell, you might not. You'll meet people, give business cards and get valuable feedback from customers. I tried with this kind of attitude, but it was not so bad, especially when I returned with so many notes about what customers were looking at and what comments they were making.
Are you aware there is a Team specifically for Craft Fairs? Lots of advice and tips and help here:
https://www.etsy.com/uk/teams/8070/craft-fairs-its-a-livingGood luck!