Setting up and correcting the profiles, deciding what is worth posting, and pointing the whole thing back at pages on your own site.
Social media marketing here means three things. Getting the profiles themselves correct, which is duller and more valuable than it sounds. Deciding what is actually worth posting for a business your size, which usually means less than you might expect. And making sure the whole effort points back at pages on a site you own, so the audience is not accumulating inside a platform you do not control.
The profiles come first because they are the part that is measurably either right or wrong. The business name, the category, the service area, the description and the link all have to agree with each other and with your website. When they disagree, a business becomes harder to place, and that is a problem search engines feel as much as customers do.
The posting comes second, and it is a narrower job than it sounds. A small business does not need to be on every platform, and it does not need to post daily. It needs to be present where its customers actually are, saying things worth reading, often enough that the profile does not look abandoned.