I was reading a post on the Hunter forums that asked a simple question: how do I separate my beloved hunter from the millions of huntards out there. The reply was a resounding: learn to play your class. With that in mind, I was excited to find someone had created not one, but two excellent guides to help newbie Hunters with the basics.
Alanoymous of Vek'nilash is responsible for creating both 'A Guide To Choosing A Pet - BC Revised' and the follow up 'A Beginners Guide to Pet Taming, Training and Care.' In the first post, he covers the wide range of pets available for various PvP and PvE situations. He also recommends the best pet in those scenarios. Then in the second post, he talks about what is involved in keeping your new pet happy and well-trained.
If you are looking for more in-depth information about pets and their abilities, you can also check out two well done hunter pet sites: TKASomething and Petopia.