I play Necro-only stuff, and I've gotten a small collection of Zombie hounds going (7). I know they're good figs, but with all my trial and error I still cant seem to master them, even in conquest they arent working. Can someone please give me some friendly advice for my cute little puppies?

Mutty mutts should be used for what they are - zombies. Conga line them up behind an LI unit ( perhaps the nightwitch who will be recycling them ) and let them charge in when in range. They'll bite it quickly, so have the witch ressurrect it quickly and repeat.

Use a Zombie Baron, so that you can ML a hound and Necro it with full health because it is a zombie. Zombies and Skeletons raise up with full health.

use them as chargers...that may work nicely...

-Liege

one way that works (old formation around here, somewhat easy to counter) is nightwitch artillery supported by hound counterassault. Don't focus on attacking with the hounds. Focus on shooting with the witches, and keeping bad (good?) guys off them with the dogs.