The most efficient way to level is to camp a spot of mobs one level below you and keep killing. The way I determined where to go next, after I dinged, was to use the
thottbot NPC search.
You're level 16 so enter in level 15 to 15, select Horde: Aggresive, then hit Find. Sort by Kills. Choose a horde zone. I see Theramore Marines are a good choice. Must be a lot of them, and with another minute of research, you can see there's even a quest associated with what they drop. The quest is
the Guns of Northwatch.
Happy Hunting.