Summarize the following:
Strong-smelling perfumes or colognes may be bothersome to him. The scent of a dog may be especially unsettling. Calmly petting him and allowing him to rub up against your hand will relax him. You may need to spend extra time on this step, depending on if your cat has a calm or skittish temperament. A cat can be held by the scruff with a collar on, but this is not recommended unless you are experienced with handling cats in this way. Although the scruff is flexible, the collar is not, and you might tighten the collar around his neck by accident. Having your cat on a sturdy and even surface, such as a table or counter top, will allow you to scruff him more easily. You could also use the floor as a supportive surface, if your cat seems to be more comfortable on the floor. Rest your hand at the back of your cat’s neck and gently grasp the loose skin in this area with your entire hand. Grasp as close to the ears as possible to lessen the chances that your cat will struggle or attempt to bite you.  Your cat’s ears should go back slightly when you grasp the skin right behind the ears. This will let you know that you are grasping in the right place. When you tighten your grasp, the skin should still feel relatively loose in your hand. If it feels tight, you may have grasped too much skin; loosen your grip slightly. Your cat will probably let you know if you are holding the skin too tightly. Do not grab too little scruff. This could cause you to pinch your cat’s skin. Re-adjust your grip to pick up more skin. Unless your cat is very aggressive, you should notice that he doesn't mind the grasping at all; he might even become very still. Sometimes this alone is enough to stop your cat from doing something you don't want him to do, or to calm him while you clip his nails or give him medication. Before attempting to lift your cat by his scruff, remember that cats, especially older ones, typically do not need to be held this way. Unless it’s a mother cat carrying her young from one place to another, cats usually do not need to picked up by the scruff. If you need to lift your cat after scruffing him, keep in mind that this will be easier with kittens because of their light weight. Lifting a heavy cat by his scruff could place extra tension on his neck muscles and skin, which would be uncomfortable and painful for him. To avoid this tension, providing extra support for his weight will be needed.  After grasping the scruff of a heavy cat, fully support his back end with your other hand. Depending on the size of your cat, you may need to wrap part of your other arm around his hindquarters.  Pick him up only when you are securely supporting his back end. Although scruffing is not painful for your cat when done properly, it can become uncomfortable if done for too long. Also, keep in mind that even the most patient cats will get tired of being held this way and may try to swing around to loosen your grip, or kick you with their back paws.  It is important to remember that your cat is essentially trusting you in a very vulnerable position. If he senses that you are being too rough or are anxious, he may not want to cooperate with being scruffed. Unless your cat feels like he’s being attacked, he should just hang there and look at you, waiting for you to put him down. Some cats will vocalize softly, as if to say "Hey, I'm not the biggest fan of this, so let's get this over with soon." If you have lifted your cat, release the scruff after gently putting him back down gently on a supportive surface.  Provide positive reinforcement afterwards to reward him for having good behavior when being scruffed. Examples of positive reinforcement include petting, talking, and treats.  Do not release your cat's scruff by dropping him. While a healthy cat won't get injured in this way, he will learn that you are too rough and he might not be as cooperative the next time you pick him up by the scruff.

Summary:
Remove any scents from your body that may be offensive to your cat. Allow your cat to become comfortable with you before you try to scruff him. Remove your cat's collar, if he has one. Place your cat on a supportive surface. Scruff your cat when he is relaxed and awake. Lift your cat by the scruff. Use extreme care in picking up your cat by the scruff if he is heavy. Scruff your cat only for only as long as necessary. Release the scruff.