Finishing Native quests with a positive outcome for them is the way to achieve this. The attitude towards you needs to turn "Friendly".
Most are on side quests.
Main Quest
The Battle of the Red Spears
• Must follow Siora's path
The Demonical Cult
• Must follow the nervous man without fighting him
Side Quests
Siora's Quest "Find Queen Blánid"
Attack on Caravans
• Convince them to leave without bloodshed (high charisma helps here)
Inquisition
• Just follow the quest through
Logging Expedition
• Another simple quest. But when it comes to the hunters. You MUST make them confess through dialogue.
The Blood Prince
• Release the Slaves. This quest is ridiculously annoying on Extreme difficulty, make sure you take a few resusitation potions and take Kurt with a weapon that does high shield damage.
Once the outlined quests are done the trophy should pop.