Do not adopt too many pets at once. While it is tempting to help everyone, a full shelter can quickly become overwhelming and stressful. Start with 1 or 2 animals to maintain high care levels.
Take dogs to the dog park for walks. Walking a dog until their "Fun" meter moves from red (negative) to green (positive) is the most consistent way to keep them happy. Acquiring the Game Animal Shelter Free Download (v1.2.7 & DLC)
The introduces younger animals that require specialized care. Do not adopt too many pets at once
When putting an animal up for adoption, match their likes and dislikes with the potential owner's requirements as closely as possible for the best results. Animal Shelter Free Download (v1.2.7 & DLC)
Expand your shelter by adding better facilities.