Are you particularly good with animals -- dogs, in this case? If you are, and you're looking for a great side business, consider this: many new dog owners didn't realize that they would have to put a lot of time and effort into training, and are now either stuck with a disobedient dog or are wishing they could stop and have some intense training sessions. Luckily, you can step in! Offering training services in your own home or backyard is a great way to make some side money and work with animals.
Make sure you have the facilities. It would be a huge mistake to have five or six dog owners sign up for your training class, only to realize that you've got no place to keep all those people and animals! If you live in an apartment, you should probably find somewhere else to go. If you've got a house with a backyard, your lawn should do just fine, so long as it's fenced in. A home gym or large garage will also serve as a training room.
Figure out if your customers will pay by pet or by session. If you choose to have owners pay per pet they bring, then have a schedule set for a specific number of weeks they're paying for (this involves making up somewhat of a curriculum, where all the owners present will be working on the same techniques with their dogs). If you choose to have them pay per session, it'll be easier for an owner with a more obedient dog to just drop by for one or two sessions to brush up on things, while the crazier canines will get more training.
Have a course schedule set out over a certain number of weeks. This way, people can schedule ahead of time when they plan to show up. Make this schedule public wherever you advertise your services -- on a flyer or online -- so owners know what they're paying for before they shell out the money.
Focus on training the owners more than the pets. It's not really your job to get the dogs themselves obedient -- it's your job to show the owners how to do so! You need to know how to interact with people and coax them into shouldering the responsibility of their pet's obedience themselves, so brush up on your people skills as well as your dog-whispering skills!
Check out GarageSaleCow.com for some more great ideas on how to earn a little extra cash!