Can someone give me a 'how to Nurgle'?

I'm an experienced player, but haven't tried Nurgle before.

So I thought I'd give it a go. And then got wrecked by Mother Ostyanka. Tried another campaign - got wrecked by Imrik.

So ... what a I missing?

I mean, Nurgle's clearly pretty different to my usual fare, and ... I think fairly unusual overall, being a relatively slow moving melee faction?

I've gone with Kugath to start, and figured leaning on Nurglings and the 'make them regen' aura was the way to go. Seems reasonably viable, but does end up with your long range lord basically in melee if you do that and certainly far too close to any ranged firepower for a large model.

So I guess ... am I doing something wrong? Clearly I need more fast units to handle archers especially, but I'm early enough that 'a few' hounds don't really do the trick.

So what should by 'early' army look like composition wise?