Do you have a helper? If so, the best position I have found is to keep them draped across the helper's lap, and to come perpendicularly to the nail with the grinder parallel to the floor. This is assuming that you use a dremel, and not scissors. Keep the dog busy with a smelly and soft treat in the hand of the helper, letting the dog lick and nibble around it. Ace quite likes soft cheese for this purpose.
Soak the paw in warmish water beforehand to get the nail a bit softer. This makes it easier for the dremel, but also for the dog as he'll feel slightly less vibrations coming from the contact point of dremel to nail.
For the pad fur, I usually just hold Ace on my own lap, on his back, with his head towards my tummy. I use a ladies' electric trimmer on its finest length to get the perfect cut. I do not require food distraction for this, and Ace usually ends up falling asleep.
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