Best advice is to grab the quill as close to the skin as possible with a quality gripping device like a needle holder. Leatherman will work.
Might need to sedate dog depending on numbers or location of quills. When removing quills make sure to safely dispose of them so they don’t end up on your clothes or another dog finds them to roll on. A sharp tug will get 98% out. Keep looking for several days to find the hidden ones in a long haired dog. Good oral exam is needed. The worse one I worked on was sedated for over 90 minutes while we removed 600-700 quills from the head and mouth, front limbs and chest. There had to be a naked quill pig somewhere. The male littermate had only 70.
Do not need to clip them. Not the worst confrontation I dealt with.