Practice, practice, practice.
My father told me that I was never going to get a topknot in Max's hair. It took about a week for him to settle down.
I agree with the advice given above to work when your pup is tired out and to give treats and encouragement. We use a lot of massage therapy and training to sit still, go down, and ideally rest the head on a pillow like the show dogs. Practice touching your pup all over from ears to paws every day. This helps acclimate pups to touch and teaches them to relax when they are being worked on.
I trained my boys to understand that to go for a walk (their favorite activity in the whole world), they had to have their topknot done.
Don't give up.