Wikipedia Resources

Getting Started 

The Wikipedia Adventure 
Interactive guide to learning the basics of editing.

Introduction To Talk pages  
Explains how to use a Talk page to leave messages for editors.

Plain and Simple Conflict Of Interest Guide
Provides lots of information about what to do when you have a conflict of interest and how to make requests.

Teahouse Q&A Forum 
A newbie-friendly forum to help new editors become familiar with Wikipedia rules & guidelines, ask questions, and develop relationships.

Formatting

Citation Quick Reference
Basic citation formatting for news outlets, books, journals, and other commonly cited sources. 

Wikipedia Coding Cheat Sheet
Table of the most commonly used wikitext formatting.

Research

Reliable Sources/Perennial Sources List
Editors have compiled a "non-exhaustive" (but still really long) list of sources whose reliability and use on Wikipedia are frequently discussed. The major news outlets and publications are all covered here, along with many niche tech and industry sources. 

General Notability Guideline
Basic criteria for assessing whether or not a topic is suitable for a stand-alone Wikipedia article. 

Tools

Pageviews Analysis
A suite of tools that allow you to analyze page views and unique device statistics for Wikimedia Foundation wikis.