Hi,
There's a few potential ways you could generate leads from Facebook but it's difficult to predict the results without doing any testing.

As you are looking to advertise a local business, the first and most important thing is to use the most precise targeting. Not only should you narrow it down by the city of yours, but also by the age and even sex of potential clients, based on your current clients profile (say women aged from 50 to 60).

Someone mentioned the problem of attracting fake followers to the page and there is some true in it, but it can easily be avoided with clever advertising. 1) you could try out advertising a Facebook Offer to people around your area, offering a big discount for first time clients - this will easily help you identify the leads coming from Facebook. 2) if you already have an email database of at least 200 clients, you can use it to create a Facebook Custom Audience and then a Lookalike Audience - based on the profiles of your current clients, Facebook will identify potential other FB users that should be interested in your service the most. 3) depending on the traffic to your website (at least ~1000 visitors/month), you can also install Website Custom Audiences - by doing this, you will be able to advertise (remarket) to every single person that visited your website, which is really powerful.

If you wanted to discuss it further, let me know and I'll be glad to help!

Best,
Adomas