>>532437387
I typically go West as Archaon, I even have a save with him still from a few days ago that I've paused; been doing others currently. Tamurkhan typically holds up but doesn't declare war on me in my runs. South usually okay at least for a while. The Norsca there typically dies early to the Chorfs but Arbaal holds up and the Chorfs go to Kislev/Malakai. But yeah you want to kill the first minor Slaanesh first then Boris ASAP, he's the hardest part early game. Then I wipe out everybody on the way to Malekith and Vassalise all Chaos I can.

Be sure to check recruitment in each province you can each turn, even if you don't own the province. For example in the aforementioned campaign I had a couple of armies roaming around to pick up good units (e.g. giant, manticore, aspirings) from neighbours and owned territory to just feed into Archaon's army. Always have maximum gifts up, too, Archaon's soul income is insane and you can afford to keep all slots filled permanently.

Who specifically declares war on you each time that isn't obvious (e.g. Boris will declare war on you)? I find Archaon campaigns early game are samey, it's up to me to make them different (e.g. going South instead).