How do multiple factions work

[Busher]

I'm currently getting decent xp off of Kizdean. I'm lvl 21 and he's 18. I'll keep this up for a while and see.
Part of the quest in in Najena with Tolkar's daughter who is on the same faction, so any "trick" will have to work indoors also. Might try the Ball of Golem Clay if I don't seem to be getting anywhere after a level of killing Mr. Gix. I am looking forward to some nice Blackened Teir'Dal at least.
The wiki says it's 10 faction points per kill, so that's not bad.
I am threatening, not scowling, so an amulet "might" get me to non-kos, but I kinda doubt I could do the quest at dubious.
Thanks