How should I properly hold a cat by the scruff to ensure their safety and comfort?

To properly hold a cat by the scruff for safety and comfort, gently grasp the loose skin on the back of their neck with your fingers. Support their body with your other hand to prevent discomfort or injury. This technique mimics how a mother cat carries her kittens and can help calm and relax the cat. It is important to use this method carefully and only when necessary, as some cats may find it uncomfortable or distressing.