The best thing you can do is to adopt a pet from a place where they normally kill animals after a certain period of time.  There are some places that will not put down animals unless there is a serious need for it, but there are others that only hold animals for a few days.  By rescuing an animal from such a shelter, you ensure that they will have a longer life and can remain happy with you.  Animals have feelings too; we may not understand the extent or depth of them, but they unarguably exist.

It is because of this fact that laws are around that prevent animal cruelty.  Nonetheless, it happens anyway, and thousands of animals are abused each year.  There are ways you can combat this, other than the aforementioned way of adopting an abused pet.  Many organizations have formed, such as PETA, that protect animal rights and help prevent abuse.  By donating to or volunteering for such a business, you can help them achieve their goals, and you can do your part to improve the world in some way.  It only takes a few dollars to make a difference, so make donating a regular part of your routine.

You can also buy from organizations that explicitly state they put some of their profits towards helping animals.  Businesses such as the The Animal Rescue Site put the majority of their profits towards feeding and helping sheltered animals, and they even offer the option of helping just by clicking a button (which provides a small amount of food derived from the revenue of the website).

If everybody does their part to help the animals and people of this planet, then we can easily achieve our goals and see a brighter tomorrow.  It is when individuals falter that we all falter, so do your best to help, and you can go to sleep knowing you have satisfied the responsibility given to you by life.