Building tools for SMBs. Tips on finding my first customer

Hi IndieHacker community, first time poster, and long time lurker.

I want to validate a product idea that I am building for small and medium retail businesses -- and I'm not quite sure where to start to engage with potential customers.

I want to talk to and sign up 3 to 5 small businesses to work with us on a beta. Here are things I have already tried --

(0) Built out a survey for business owners to sign up -- smartmarkup.app
(1) Reddit posts on business related sub-reddits
(2) Started a Twitter account and tweeted at some business related accounts

Any other things I should be trying?