Many people have the misconception that it takes a lot of effort and time to help animals. That you have to do something big. But this is not true at all. There are many SMALL things you can do that will make a BIG difference.
Make sure that your dogs, cats, and rabbits are spayed and neutered. Millions of unwanted pets are put to sleep in shelters. If you spay and neuter your pets, you won't be contributing to the problem.
Participate in "Meatless Monday", and don't eat meat each monday! It's a really simple yet very helpful idea!
It is also really important to educate people about the cruelty that is happening and how to help stop it. You can do this by passing out leaflets and brochures, putting posters on bulletin boards, having a voicemail about an animal issue like animal testing or factory farming, and just mentioning the rights and welfare animals deserve when you get a chance.