Last week we published the JCR Query cheat sheet as part of the official AEM documentation:
https://experienceleague.adobe.com/docs/experience-manager-65/deploying/practices/best-practices-for...
it is appplicable for AEM 6.5 and AEM as a Cloud Service, but the majority of it should be good also for earlier versions down to 6.0.
For different type of queries it contains samples which are are the most performant to achieve the expected results, plus the requirements towards the index backing these queries. It contains these queries so you can copy&paste them, has a number of helpful links, and its printable so you can pin it to your wall. And it's the a good learning source for the 3 supported query languages QueryBuilder, XPath and SQL-2.
Have fun!
Jörg
