Dr. McMourning is, no doubt, an awesome master. He's a total beast in melee (albiet fragile if handled incorrectly), he has some devastating spells, and can summon the more nasty monsters in the game. I would definitely recommend having a rogue necromancy proxy as well as a flesh construct (or two, depending on your playstyle) on the side lines ready to join the fray.
As far as models to start with, it's always good to bring the zombie chihuahua and a couple of canine remains. The dogs add a lot of flexibility to your crew, whether they're racing forward to grab objectives / table quarters, or staying behind to be slain by McM himself to bolster the undead ranks with fouler creatures. I also never leave home without one rotten belle and a convict gunslinger. These two in tandem are an absolutely devastating duo. You really can't go wrong. Punk zombies and crooked men also often find their way into my lists based on what the strategy / schemes are for the match. Crooked men can be a bit tricky to master, but once you have the hang of how they work, you'll be happy you learned how to use them.
Hope this helps!