A Guide To WDQS: A long-form introduction to WDQS. You can start with no knowledge about Wikidata or SPARQL at all and hopefully emerge knowing how to use WDQS for awesome queries. Note that it is perhaps somewhat verbose, and certainly not intended to be useful as a quick reference.
Problems: I maintain a list of some SPARQL queries I wrote that can help you to find problems in Wikidata. Some of the problems could be fixed fully automatically, others need manual review.
wdqs.sty: A LaTeX package that emulates the Wikidata Query Service’s syntax highlighting (font + colors). Could be useful for presentations.