How do you discipline an autistic toddler?!

Figuring out how to discipline my son has always been a real challenge for me too. He is almost 3 and he has just now somewhat started to realize what NO means and listen to me when I say it. When I do say no I make sure and exaggerate my mad face and exaggerate my voice and make sure I have his face in my hands so he is looking at me. I exaggerate because he has such a hard time understanding emotions/faces. Then I explain why we don't do whatever he did in the simplest terms possible. That's about all I do to discipline USUALLY. If he gets really mad and tries to hit at me or pull my hair I hold his hands down firmly and tell him NO HIT! He gets that that is a punishment because if your kid is anything like mine he doesn't want to sit still for more than 2 seconds so he doesn't like his hands being held down even if it's only for a sec.