Awesome guide Baalz, as usual.
I'd like to point out one neat trick that few apart from LA Atlantis (and some of the Heims) can pull off. I'll preface it by mentioning that most raiding nations have a lot of trouble reinforcing after the initial raid, and almost no ability to break down castle walls.
The trick:
Surprise-attack a coastal fortress with sailing raiders while simultaneously hitting it with
an amphibious Bane Venom Charm holder, or (later on) Black Death/Tidal Wave . The following turn, cast enough Carrion Reanimations (3D, so 1/4 of your Angakoks can cast it) to turn all those corpses into Soulless @ 100 per 10D. 500 Soulless will bring a mage-factory down pretty quickly. Now you've got a base of operations on your opponents side of the lake 3 turns into the war. Worse comes to worst, demolish it as you sail away.
P.S. Carrion Reanimation also gives you something to do with all those dead R'yleh chaff. 
P.P.S Edited yet again in response to Max's comments.