The Landsmeet itself is pretty simple. You only have one vote going in and need to secure the rest. There will be a bit of a debate and you'll need to defend yourself.

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The really important thing is to not mention that Loghain left Cailen to die. We can't prove that and it makes us look weak. It will cost you a lot of support. Just stick to the Blight.
Make sure that you tell Loghain that the Blight is the real enemy, not Orleas. This will confirm Arl Wulffe's vote if you spoke to him in the Tavern.
Mentioning Arl Howe's dungeon will help if you finished the Tortured Noble quest. Bann Sighard will back up your claims.
Mentioning the assassination attempt will help, if you finished the Lost Templar quest. If you talked to Imeric in his cell, he explains that he was the one who captured Jowan in the first place. His sister will reveal that Jowan had to have been released by Loghain's order.
Freeing Vaughn earns you a free vote.
Completing the Trial of the Crows quest line will earn you a vote. The noble who's son you rescued will just state that you helped him with a family matter of great importance.
Anora will either defend or incriminate you in the matter of her “kidnapping.” It depends on whether you promised to support her.
One person will automatically vote for Loghain and one will vote for the Wardens.
After everything is said and done, the vote will be called. If you followed my guide, then you'll win. This saves you a fight. If you lose, then Loghain will try to detain you and Eamon will call for resistance. You'll then have to wound Loghain to make the nobles call for a duel.
If you win the vote, Loghain will demand a duel before he steps down.