Without more information we can only give you generalized advice for a local business.
But in general, what tends to work is:
-Focus keywords on intent rather than anything (i.e. “get a haircut” instead of just “haircut”, etc)
-Social proof. Especially if you have good reviews on your Google My Business profile (ideally 100+ reviews with 4.5 stars average or higher). You can tie it to your Google Ads account so it will show with the ads and will also show up more on Google Maps searches.
-You should also have some kind of automated system in place to ask for reviews after appointments, this is really easy to setup and it will help your paid campaigns and organic results on Google Maps.
-Customers respond way more to images and videos. Get photos of any really cool hairstyles that you’ve done, videos would be even better. They don’t need to be super professional creatives, taking a quick 30 second video a smartphone to show the hairstyle and maybe ask the customer to say something positive about your business.