the trick is using camera to your advantage , u only can tab-target what you see in your SCREEN , if u want to avoid targetting the mobs on the far end of the zone , move the camera a bit , i used that trick a lot in raids to avoid tab targetting adds or just 2 add and not the boss ect....however sometimes u forgot about it and target the mob that is faaaaaaar away and then the one next to it

Another tick is using the enemy list , if you or any1 in the party has threath to a mob will appear on that list.