What do you recommend to sign up local businesses?
Is asking in person is a good approach or are local Facebook ads better?
In a service I had in the past EVERY local business I signed up was in person, not even one signed up through facebook ads, although I tried.
So for me I would say in person 100%.
Also it's a great way to get feedback, you will be amazed how much people are willing to help if you are kind.
Just be careful not to get biased false positives for feedback.