I’ve been using schema.org for a few years now, but haven’t yet logged any notes and usage advice. Schema.org gives websites a practical, structured data approach for communicating the meaning of their content in finer detail than they could with native HTML alone. Google etc can then parse this and use it in their interfaces to offer users a richer view of your data.
Schema.org lets you pick from different types of properties for describing your content, such as book, person, place or event. Alternatively a more generic article you might use BlogPosting.
Schema.org is still current and celebrated its ten year anniversary in 2021.
One bit of troubleshooting advice worth mentioning is to validate your page using validator.schema.org. Thanks to Liam who recently pointed out a schema issue on my site, which reminded me I need to use the validator any time I make changes to the relevant markup.