Enter the Burning Forest from the west or the south (to shorten the route). Take out the patrols first and the two larger groups of Charr next; these should be fairly easy as they are passive until you come close to the quest marker. The third group looks easier, as it seems to contain a lone boss named Strout Flamebourne. However, attacking him spawns a group of Charr Effigy, making things more interesting, as they spam Breath of Fire.