You should publish the microformats that themselves have reasons why to use that resonate with you, e.g.:
The IndieWeb makes heavy use of:
There is a fuller list of implementations on the microformats wiki. Here are some used by the indieweb community:
Are microformats an API
Q: Are microformats an API?
A: No, microformats are more like the information returned from an API.
HTTP GET of a particular URL of a website can be an API. microformats in the resulting HTML provide the information you might otherwise get from a bespoke API.
Thus combining HTTP, good site URL design, and microformats, your site can be your API. No separate XML/RDF/JSON/??? API endpoints needed. At least for readonly. For a write "API", see micropub.
A: Actually, yes, microformats are the simplest way of providing a read-only API, also known as "your website is your API".
Why not APIs
Main article: API
Q: Why not APIs instead of microformats?
A: See API, in short: