- Learn how to use the available resources for tag analysis and usage
- Find a tag in OSM that you don't recognize
- Look it up in the wiki and read about how it's used
- Write a query in Overpass to find how many instances of the tag exist where you are
- Tip: use the Wizard to construct the query for you; the query language is complex
- Look up the tag in taginfo to find how many instances of the tag exist globally
https://wiki.openstreetmap.org/wiki/Main_Page
Use the wiki page to learn how to use tags.
https://taginfo.openstreetmap.org/
Read more about the tag system here, https://wiki.openstreetmap.org/wiki/Tags
Check out the user manual, https://dev.overpass-api.de/overpass-doc/