Are there animal control officers in your city? If so, give them a call and let them know you are wiling to adopt a rescue animal should they come across one. You can also contact local vets. That has been my biggest source of rescues. Many owners who don't have the money for surgery or medications will surrender an animal rather than having it put down because they cannot afford care and vets often have staff who work to place these animals in rescues before they euthanize needlessly.
You can also get personally involved, trying to "liberate" abused animals from petstores. Should you find a neglected, improperly housed or downright abused animal, start making phonecalls. Get the attention of animal control officers, local media, animal rights groups and basically anyone else who is willing to listen. Let them know that you can handle the special needs of this animal and it will die if left in its current environment. It is an uphill battle but every animal that ends up in a proper home after suffering through some of the nightmare petshops is a major victory. Far more so than purchasing the animal to "save" it so that the store can use the profits to acquire a new animal to live in that same bad home.
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