Making NPC's transparent using Konduit client and Gimp
When you hold Shift and right click an NPC, you're given an option to 'tag' it which forms a complete outline.
Using gimp, or whatever software you prefer, it's much easier to clear out the background.
The only issue is that sometimes, the white outline isn't entirely connected. Capes and some 2-handed weapons can cause issues, but otherwise, it's a fairly flawless outline for most NPCs.