To earn reputation with significant factions in the Broken Isles in WoW Legion Remix, completing world quests is the easiest method. These quests unlock early in the prologue and each faction has a rotating world quest timer.
Upon completing four quests for a chosen faction, you can meet with their emissary, who also serves as the quartermaster, to receive rewards, including reputation-boosting consumables.
Complete four quests for a chosen faction to meet with their emissary and receive rewards.