I can't do it bros, I can't leave the bronze silver gold rooms...

Guides
A list of guides taken from the pastebins in the OP, transfered to a more "readable" format

General

Mahjong Live Pastebin

A thorough guide to everything mahjong. Made back in the /jp/ days, it hasn't seen much update in a while but is still perhaps one of the best infodumps around.

I'll try to update this with newer information every now and then.


Mahjong Equipment Buying Guide

Everything you need to know about owning a mahjong set irl.


No Fu Mahjong Teaching Method

From the writer of Hatkagi comes a mahjong teaching method that alledgedly "works great even on kids at the park". A slow crawl approach to teaching the game.


Download Abema VODs

Short instructions to downloading Abema VODs. Learn from the pros.


So you want to play sanma

A guide for people trying to get into sanma (three-player mahjong).

Strategy

How to play Video Game Mahjong

A quick and (relatively) easy guide that teaches you enough mahjong to surf through Mahjong Soul's bronze room. Not to be taken as a consistent mahjong strategy, this is meant more for beginners wanting to get a feel for the game.


Daina Chiba's Riichi Book 1

Do you want to stop being bad at mahjong? Read this. RB1 is essential mahjong reading. Teaches tile efficiency, defense strategies, yaku chasing and everything else to bring you to the level of an intermediate player.

You can also read it online.


Riichi Mahjong Strategy

A book by Fukuchi Makoto and constantly translated by a kind anon. The book is heavily focused on tile efficiency, with a highly digital (analytical) way of thinking. All of the later material about push-fold judgment and discard reading is based on good tile efficiency.

You can also read it online.

Mahjong Soul

Introduction to Mahjong Soul

An introduction to the ins and outs Mahjong Soul. Go and familiarize yourself with how things works before selling your soul. Also a good guide to have if you want to go through this gatcha hell without spending even a single cent.


Majsoul Plus Guide

A guide for setting up Majsoul plus, a desktop client for Mahjong Soul. Also contains an updated list of mods and extensions shared by based anons in the thread.


Majsoul Plus Modding Guide

A short guide on how to make mods of majsoul plus. Go on and stick your animu waifu in.