The best place to farm honorable kills is to stand in the middle of the map in Arathi Basin, at Blacksmith.
If you stay there, you will gather all the honorable kills done by your team from all the map. To do a test, you can just stay there and check the final scores. Even if you haven’t killed any player, there is a very high chance to finish the battleground being the player with the most honorable kills.
A favorable battleground where your team dominates the fight gives usually 50-80 HK. If you play a stealth class, you can just stay around the blacksmith and try to ninja the flag.
100.000 HK gives “of the Alliance/Horde” title. When you reach 250.000 HK, you will get the “Bloodthirsty” title.