Here are some useful articles and white papers (in no particular order). This is just a partial list of many useful articles about Tableau and visualization in general:
Five things I wish I knew about Tableau when I started (This is an older article, but still useful and relevant to the current version.): http://bit.ly/5things-tableau
Top 10 Tableau Table Calculations: http://bit.ly/top10tablecalcs
Understanding Level of Detail Expressions: http://bit.ly/UnderstandingLOD
Top 15 LOD Expressions http://bit.ly/top15LOD
Tableau and R Integration http://bit.ly/tableau-and-r
Visual Analysis Guide Book http://bit.ly/vaguidebook
Tableau Drive Manual http://bit.ly/tableaudrivemanual
Designing Efficient Workbooks http://bit.ly/efficientworkbooks
A Guide to Creating Dashboards People Love to Use by Juice Analytics bit.ly/DashboardsPeopleLoveToUse
Design Tips for Non-Designers by Juice Analytics http://bit.ly/designtipsfornondesigners
Designing Effective Tables and Graphs by Stephen Few http://bit.ly/stephenfew-effectivechart
Tapping the Power of Visual Perception by Stephen Few http://bit.ly/stephenfew-visualperception
Bullet Graph Design Specification by Stephen Few https://www.perceptualedge.com/articles/misc/Bullet_Graph_Design_Spec.pdf
Implementing Tableau Server: Top 10 Pitfalls http://bit.ly/tableauserver-top10pitfalls