Never discipline your dog when you're angry. In the natural world, a pack leader is always calm and assertive, or the others won't follow. This is why, when you see people in the dog park screaming their heads off, the dogs won't respond. This doesn't mean you shouldn't use your voice to get the dog's attention. When I want a dog to come to me, I say, "Hey!" but not in an angry way. If I said it angrily, I would be undermining my position of authority. If the dog doesn't listen, I move closer to him instead of yelling louder. Dogs communicate through touch, eye contact, and energy.
A pack leader can bring a misbehaving dog in line with a stare. Many people can't do this, though, so the leash is a good tool. Of course, you have to use it properly. Correcting by pulling back on the leash is bad. Instead, pull it to the side. When you pull back, the dog resists you. When you pull to the side, you unbalance him and break him out of his undesirable cycle. Think about fighting another guy. If you pull him backward, he'll resist and want to fight more. If you push him to the side, he'll look at you and say, "Why'd you push me?" His cycle is broken.