Best beginner resource:

Data Visualization Catalogue 

Excellent library of resources, Dataviz :

DataViz Cheatsheet 

Visualizing Percentages 

Sizing Circles for Data Visualization 

Chart Chooser 

Chart Chooser Cards 

The Graphic Continuum

Financial Times Visual Vocabulary

The Data Viz Project 

Interactive Chart Chooser 

Graphic Cheat Sheet 

How to Choose Your Charts 

The Chart Guide 

Power BI Visuals Reference

Classification of Chart Types 

Chartmaker Directory 

Visual Analogies 

Visualization Universe

Data Visualization Checklist 

Play Your Charts Right 

From Data to Viz 

Qualitative Chart Chooser 

Which Visualization Quick Reference Guide