Stata
StataCorp's YouTube Channel tutorials for data cleaning/management, analysis, and visualization in Stata.
Online Stata Tutorials, Princeton
A full course on Stata, the University of Wisconsin-Madison
Stata Cheat Sheets and More Resources, by Tim Essam, Laura Hughes, Aaron Chafetz & Doug Johnson
Visualization Resources from the Stata Blog: Stata's "Visual overview for creating graphs", Plotplain and Plottig by Daniel Bischof, Stata schemes
More? Browse Stalalist, Stackexchange, or Stackoverflow
Python
Introduction to Data Analysis with Python, by Monash SoDa Labs (an excellent way to start)
Web Scrapping in Python, by Monash SoDa Labs.
Fuzzy matching at scale: PolyFuzz by Maarten Grootendorst. PolyFuzz performs fuzzy string matching, string grouping, and contains extensive evaluation functions. While some methods will work only on relatively small samples, some methods (e.g., TF-IDF) can be used for fuzzy strings matching with large datasets (millions of observations).
More? Browse Stackexchange, or Stackoverflow
QGIS
More? Browse Stackexchange, or Stackoverflow
Writing in Economics (term paper, Master or Honors' dissertation)
Writing Economics by Robert Neugeboren with Mireille Jacobson (Harvard FAS)
A Guide to Writing in Economics by Paul Dudenhefer (Duke University)