Valid markup is only the first step
Separate vocabulary validity, feature requirements and actual search appearance.
Three different questions
Can a parser read the markup? Does it meet the requirements for a particular Google feature? Will Google actually show that feature? These are different questions. CheckMySchema handles deterministic parts of the first two for its supported profiles.
Choose the right feature guide
Google’s search gallery is the index of supported structured-data features. Each feature has its own eligibility conditions and property requirements. A Schema.org type that is absent from a Google profile can still be useful to other consumers.
Finish with Google’s tools
After correcting markup, test the deployed page in the Rich Results Test and inspect it in Search Console. A clean local report does not establish crawlability, indexing, content quality or rich-result display.
Go deeper with the official sources
Google structured-data introductionGoogle search galleryRich Results TestThis is an original explanatory guide, not an official search-engine document. Requirements can change. Follow the linked sources for full, current details.