I require a home visit, where you come to my home with your dog before I can commit to dog sitting them. We need to make sure that your dog is comfortable with me and my pack, and my dogs with them, and that you are comfortable with the accommodations for them.
I prefer to dog sit small breed dogs (under 25 pounds) because my dogs are small, my house is compact, and tiny dogs can easily be injured by even the friendliest large dog. I might make an exception but would need to meet the dog first. The safety of the small dogs in my care is paramount.