This is an in-depth guide to help people learn to master Darkest Dungeon. It started as a collection of basic tips and strategies, but at this point it’s a fairly complete guide to the early game (levels 1-3 or so), and should answer most of your questions, perhaps even ones you didn’t know you had. Read it and you’ll understand how to keep and build a viable group of adventurers, get past all the early pitfalls, and understand the basic game systems.
It won’t cover the late game (levels 4-6) because the game is still in Early Access and, while the level 1-3 content seems mostly finished, right now the level 4-6 content doesn’t, so anything I write could still get significantly changed, so there’s not much point in going into too much depth. Because this guide may need to change, I’m not going to include a lot of fancy videos — it’s a lot easier to edit text!
If this Darkest Dungeon guide seems too long, don’t freak out; there’s a lot to be said for just diving into this game, playing it blind, and letting the chaos happen. But if you run into a problem, read this over and it should help you figure it out.
EDIT: This guide is not updated for the Hound master or Cove patches, but only covers the game as it was during the first month or two of Early Access. I plan for a full update with the release of the final dungeon.