The Tableau Community Blog is a comprehensive resource containing articles on a variety of topics to help learn the ins and outs of the Tableau analytics software package.
Tutorials on connecting to various data sources can be found by selecting “Data” from the “Category” dropdown list.
Note: interworks.com is a useful third-party resource that includes overview on popular chart types in Tableau.
MakeoverMonday.com is a third-party website that offers practice problems and solutions.