1. Assess your dog's health and performance: Check the body condition of your dog. Assess the quality of life of your dog and its happiness. Take note of the eating and drinking ability of your dog, whether it is good or worse. Check your dog's body, whether it's not in any pain. Also, consider the challenges of the behavioral problem your dog might be having.
2. Making your decision: Visit your veterinarian and discuss euthanasia with him or her. Take your time before you conclude on your decision, and also seek advice from family and friends. Also, spend good quality time with your dog and make it feel good.
3. Euthanize your dog: Fix an appointment with your veterinarian, and also deal with payment and logistical decisions ahead of time. While the dog is being euthanized, you can decide whether or not to stay with your dog. Note that you should also prepare for your dog after it has been euthanized, maybe the cremation process.