For these first few sessions this is important just nip the very tip of the nail with the clipper so that there's no way you're going to cut too far and hurt him. It means that you're going to have to live with longer nails for awhile, but it's critical for the dog to learn that nailcutting might be uncomfortable but it doesn't hurt. Depending on how the dog is handling this so far, you can either start on the next foot or take him off the table for now and work on him some more later in the day. I usually cut nails as part of routine grooming. With a reluctant dog, I'll do one foot, brush awhile, do another foot, brush some more and continue in this way until all four feet are done.
Most people stand in front of the dog, pull the leg forward and try to hang on to the paw.
This just doesn't work with a reluctant dog and seems to make them want to pull their foot away all the more. Many dogs object to nailcutting because someone has clipped their nails too short in the past and hurt them. Unlike our toenails, dogs' toenails have a nerve and a blood vein inside them. When cut too short, it causes pain and bleeding. If you only cut the dead section of the nail, you will not hurt the dog or make it bleed.