Note the Austrian accent. Some syllables are stretched out, and the r sound is generally absent. Hence the Ahhnold sound with the r dropped. When Arnold said his famous line "I'll be back" in Terminator, it sounded more like "All be bock."
Pay attention to the manliness of your voice. You must drop your voice considerably to do a proper Arnold imitation.
Find a phrase that will stick with your friends, family or whomever you're trying to impress with your Arnold imitation. Arnold is famous for his one-liners, including "Hasta la vista, baby!" in Terminator 2.
Turn it up. Arnold is not a low-talker. When he speaks, it's more like a roar than a whisper.
Be able to laugh at yourself. One of Mr. Schwarzenegger's gifts is the ability to put people at ease with his sense of humor that pokes fun at yourself.
Flash a confident smile. Look at any picture of Arnold, and you'll notice his pearly whites that take over his face.