The class Discords are now the best all around source for information.
http://www.icy-veins.com/forums/topi...cord-channels/
Don't assume everybody on them is helpful and knowledgeable, but each generally has a channel for each spec. Go to your spec's channel and use the button up top to see pinned messages. This will help you figure out which posters to pay the most attention to and will lead you to the guides, trinket sims, etc. Some are better than others, but they're generally pretty good.
Some classes actually have great dedicated sites, like Altered Time for mages, but I don't know of one for DKs that's current, accurate, and detailed.
Good luck!