Probably the first thing everyone wants to accomplish when welcoming a new puppy or dog into their home is getting it housebroken. And if you didn't already know, the smallest breeds are often the toughest breeds to potty train.
The most important rule in housebreaking any dog is limiting their space. Pups in potty training must earn their space. It's true that they will not soil their beds, which is why crate training is a great method for all dog sizes. Gating dogs in a small area is okay, too. Make sure the area is waterproof or water-resistant, so it is easier to clean. For Cheryl's toy dogs, she set up an exercise pen with a potty box inside.
When Cheryl introduces dogs to the box, she first does it by action and places them in the box. Then she teaches them by cue, picking a word like "potty" and associating that word with the box. When training, she wakes up the puppies, places them in the box, and automatically uses the word she chose to cue them to go. These dogs will often just hop right out, but continue to put them back in. Never scold and never yell -- these dogs can hear perfectly. Cheryl recommends waking up the puppies -- you always want to set them up to succeed, not to fail from the get-go, and they are most likely to potty right after a nap or about 20-minutes after eating.
At night, the pen allows the dogs to have the space, potty, food, and bed all in one area, so they learn to accept the pen as a wonderful place. This makes the process a lot easier. Of course, there isn't much of a choice for bigger breeds. For these, crate training and teaching them to go outside is the best option.