The best place to start any photography career is with a local studio doing the same thing you are trying to get into. For example if there was a designated photographer for the local zoo they would be the perfect person to get in contact with.
First u have good camera urself and know how to use camera. You could use natural light, but a flash studio strobe lighting if they really want to it right and the background. if u work out of your home remember to separate workspace from living space.
Select a best camera, approximately 10-20 pixels. Go to the farm where breeding animals, taking pictures of them. You can also use photoshop if you want.
Starting a career in photography can be a difficult thing, but with persistence and a little talent, it's not impossible. The first thing you need to do is make a portfolio. Start by photographing every animal you come across, and make it professional. Then find a place to become an 'intern' or 'apprentice', and get some experience behind you.