1. It's best if you begin getting them used to their nails clipped at a young age.
2. When you do the actual cut, you want it to be nice and quick, and you never ever want the clippers stuck at the point of halfway cutting the nail. Dogs don't like this.
3. After clipping them, taking them for a walk on cement sidewalks (a good long walk) will help to file them/smooth them down a bit.
4. More frequent walks might eliminate the need to cut their nails.
What works great for us: we take our dogs back to the little creek behind our house and have them chase rocks in the water. They keep digging at them on the bottom and keep their nails filed down really nice. You can tell after the winter, that they need them cut or filed in this manner.
And, if you think that cutting dogs nails is miserable - you should spend a little time trimming the hooves of goats. Or worse yet, have a pissed off llama spitting bile at you while you're trimming their hooves. <spit> <spit> <spit> (This only happens once a year when we're also giving them a nice haircut. They don't like it too much.)