Below are some of the resources I find/have found most useful. There are many other compilations of this nature, but this is mine!

• Help:Cheatsheet – most commonly used wiki markup
• Wikipedia:Simplified Manual of Style – "overview of commonly used style guidelines"
• Citer – creates Wikipedia citation from URL, DOI, ISBN, PMID, PMCID, OCLC, or Google Books
  • Help:Citation tools – other options

• Help:Introduction to Wikipedia
  • The Wikipedia Adventure
  • Single-page guide to contributing
  • Writing better articles
  • Dos and don'ts
  • Lots of links to helpful pages about basic info
• Help:Introduction to the Manual of Style/1 (or view all as single page)
  • Help:Introduction to the Manual of Style/Manual of Style quiz
  • Lots of links to helpful pages about the MoS
• Wikipedia:Tips – "digest how to use Wikipedia in bite-sized morsels"
  • Wikipedia:Styletips – "useful advice to editors on writing style and formatting"
• Wikipedia:Task Center – find things that need doing

• Help:Wikipedia: The Missing Manual
• Wikipedia:Manual of Style

• You can almost certainly find the answer to your question by searching the below:
  • Help:Contents – for help with the most common questions about Wikipedia
  • Wikipedia:FAQ – index of FAQ (frequently asked questions) topics
• For "some locations where you can ask questions or make comments", go to Wikipedia:Questions.
  • Wikipedia:Teahouse – for beginners looking for help
  • Wikipedia:Help desk – for new and experienced users looking for help using the English Wikipedia
  • Wikipedia:Reference desk – for general (i.e., not Wikipedia-specific) knowledge queries
• Find the right place to ask for help.

• Citation Hunt – "The Wikipedia snippet below is not backed by a reliable source. Can you find one?"