AMC recently debuted the fourth season of its popular horror series "The Walking Dead." Since it's been on the air, we've seen characters beloved and vile come and go, but a constant figure all throughout has been Greg Nicotero. Mr. Nicotero started out as the show's resident effects guru, having trained with some of the best, including makeup veteran Tom Savini and the zombie master himself, director George A. Romero. Since then, he's moved up the ranks to become one of the show's executive producers and directors. And sometimes, he even plays the part of the undead himself.

We featured Mr. Nicotero in this year's Creativity 50, Ad Age and Creativity's annual list of the year's most influential innovators. When we spoke to him, he offered some enlightening tips on what it takes to look and act really undead. We present them as our treat to you this Halloween.

1) When you're not born with the undead look, customize
"There's a visual attribute to it. We always go for people who have really good bone structure. Sometimes they have big eyes. On the show, all the walkers have contact lenses. All their eyes are dead, cloudy, bloodshot and disgusting. The better their eyes read, then the more effective their look is. Often, we'll do custom dentures so it looks like their lips are peeled away, revealing more teeth, which is a visual we took from the graphic novel. Sometimes you'll look at real mummified corpses, and the lips shrivel away, revealing teeth, which is this horrific look. We mimic that."

2) Don't be a textbook monster
"We audition people and have Zombie School every year. It gives me an opportunity to see everybody ahead of time and get a gauge of what they look like and how their performance is. Our extras are unlike any extras. They're not just sitting at a table in the background pretending to have dinner and sip wine. Our extras are the guys who come up to the table, flip the table over and attack the actors, so it's really important that they can perform and take direction. So I work with them quite a bit to make sure their movements are realistic. We try to avoid the Frankenstein look where their arms are outstretched. Or someone will drag their leg and look like the Mummy or another person has their hands in claws next to their face like The Wolfman. All these people are going for the classic movie cliches, which we try to break."

3) Act (kind of) drunk
"We kind of refer to our walkers like a lion stalking an animal. It can be slow and methodical, but when there's a human nearby, they can get pretty riled up and active. And I will always tell people, if you see people walking out of a bar at two in the morning, you'll notice there's a disconnect between their brain and their feet and their arms. They think they're walking straight but they're walking crooked. So when I'm on set, I'll always tell people, keep your shoulders slumped, relax your body. If you're too tense and you're too stiff, it looks fake. I'll always say disconnect. Don't be too aware -- if you hear a noise, don't turn around quickly. Your reactions should be dulled down. It's a lot harder than it sounds or looks."

4) Don't blink
"I directed the episode in which a walker killed Dale. I was very specific with him. He had really good bone structure and he literally looked like a horrific doll. It was a really neat makeup my guys did. In editing I made sure to cut out any instances where the actor blinked.When people blink, that's an involuntary reflex, so with zombies, I try to take those lifelike performance bits away. You watch it and it's so weird, and you might not realize why."

5) Watch your mouth
"On the show, we have this flavored stain, and any time we shoot zombies close up, we make them swish this stain in their mouth. It's like cake icing. It turns their tongues and gums black. When you see someone with a pink tongue and pink gums, that looks very alive. But you figure once these walkers die and everything starts decomposing, their tongues wouldn't be pink. They would be black. I always look for stuff like that. The minute you see pink flesh underneath what's supposed to be dead and decaying flesh, for me it takes me out of the story."

6) Act like an animal
"One day I was showing a zombie how to eat human flesh. I said, 'You know when you watch Animal Planet or National Geographic and you see a hyena eating a zebra? That's what you want. We want it to be raw, intense. You're not using your hands to rip meat out, you're literally using your mouth. When you see a hyena eating a zebra and it's tugging at the body trying to wrench meat free.' They look at me like I'm crazy. I don't get it.