Dragon Age: Inquisition

For this achievement you must have the Trial - "Travel Light" turned on from the games options menu while doing the In Hushed Whispers quest. Using this trial makes it so that no supply caches will show up in the world.

This trial must be turned on before you head to Redcliffe Village to speak with the mages. I tried it first by turning this trial on and then excepting the In Hushed Whispers mission from the War Table and it did not unlock for me. Then I redid the whole thing and turned the trial on after travelling to Val Royeaux and having the conversation with Fiona about speaking with the mages. So make sure to turn this trial on right at that point or before.

This achievement popped for me after defeating Alexius and returning to Redcliffe castle for the cutscene with Fiona about the fate of the mages.

Hopefully you have an earlier save of this game, but seeing as a lot of these DLC achievements require a partial replay through it's not that bad. If you don't have the save you will unfortunately have to start a new game to get to this point.

While each of the Trails has an okay guide already, I found that I didn't read each correctly, and ended up having issues, and having to start a 3rd play through just because I mis-read the Trial of the Lovers guide. Rather than having people bounce around each Trial to determine when they need to turn it on/off I thought it would make it easier if there was a single, common description to help people.

First, there are a couple of Trials that can likely be completed using existing saves:

Trial of the Hermit - As mentioned in the original guide, you can turn on Grizzly End and go to the Emerald Graves and follow the guide there to get your 10 great bears. This took me around an hour of wandering around each time until the bear showed up, but works well.
Trial of the Tower - Since Emprise Du Lion had the 3 most difficult dragons most people will likely have a save they can use to kill the Hivernal dragon so just turn on Rub Some Dirt On It and kill the dragon. The only note on the original guide is that the Hivernal dragon is actually the bottom of the three, not the middle.

Additionally, a few other trials may be completed using existing saves, or by turning on as soon as you start Trespasser.

Trial of the Emperor - You need to turn on Walk Softly and kill 20 special foes. These foes show up randomly, so you may get all 20 during the DLC, or not. It's been noted that you need to do them in one save, so it may be easier to do them as part of the new game you need to start.
Trial of the Empress - Turn on Even Ground, and with every member of your team level 16 or higher, kill the Hinterlands dragon. Since this is the first dragon you come across most people will have killed this early on. If you are lucky enough to have a save before you killed this dragon you can work to up your level to the appropriate point before killing the dragon. For those (like me) who killed him early on and don't have an appropriate save, you will need to complete this on your second game.

All the remaining trials require you to start a new game (preferably Casual Mode to make it easy).

As soon as you have control of your character, go into Options, Trials and enable:
Fair-weather Friends
Walk Softly
Take It Slow

The goal is to get to Skyhold as quickly as you can. Don't bother opening up any other locations other than what is required for the main story. Close Rifts, capture camps and fill requisitions to get Power and complete the initial main quest storylines.

I completed Trial of the Emperor pretty quickly (before In Hushed Whispers), so once you see that pop you can turn off the Walk Softly Trial.

When you are ready to start the In Hushed Whispers trial go into Options, Trials and turn on Travel Light. Once you complete the quest the Trial of the Magician achievement will pop, and you can turn off Travel Light again.

Work your way through the main quests until you get to Skyhold. If you've not done anything other than necessary to move the story forward you should have no issue being level 4/5 as you reach Skyhold. Once the Trial of the Fool achievement pops you can turn off Take It Slow.

Once you are at Skyhold you will want to go and get all the available party members and then continue the story line until you get to the Wicked Eyes and Wicked Hearts quest. Once you've started this, the achievement for Trial of the Lovers will pop, and you can turn off the Fair-Weather Friends Trial.

Continue the storyline until you have enough Power to unlock Emprise Du Lion. Before travelling there you will want to turn on the Rest Easy trial and work your way through capturing Suledin Keep. Once the Trial of Temperance achievement pops you can turn off Rest Easy.

At this point, you are either done (if you were able to complete Trial of the Empress using a previous save), or you will need to build up your characters to level 16. Keep in mind that all your followers need to be at level 16 as well, and they tend to trail behind you, so make sure everyone is level 16 before you go back to the Hinterlands, turn on the Even Ground Trial and defeat the Frostback Dragon.

I realize that much of the above information is available in the existing Guides, but you really need to map out a complete strategy to complete this DLC with the minimum of frustration. I screwed it up and need to start a 3rd play through just to complete the Trial of the Lovers achievement. Hopefully this guide will help others avoid this frustration.