A dog groomer's salary depends on several variables. First, consider that a groomer who works in a grooming shop, vet clinic, or pet supply store generally gets a base salary. As a frame of reference, in 2010, a dog groomer made slightly less than $20k per year. You're not getting a Beemer based on that salary.
If you work for a large pet supply store, you might receive a merit bonus along with your base salary. You might trigger the bonus if you add new clients, increase the number of dogs you groom every week, or surpass your monthly sales goals. Keep in mind that the merit bonus might be split among all the groomers, and the grooming manager will probably get a larger percentage. Hopefully she's earned it.
You might also receive some sort of commission along with your base salary. The shop uses this rationale as an incentive for you to promote added services and encourage former clients to return for additional grooms. In some cases, your shop might offer you a commission-only deal. You'll have to evaluate this one for yourself. Remember that most grooming sessions last about two hours, start to finish. Decide if you can crank out enough dogs to make it worth your while.
Now let's talk about a source of income that takes some effort on the front end, but will pay off in spades. Let's say you do a terrific job for a client, and she gives you a rather generous tip, say about $20. Even better, she requests you for her dog's next beauty treatment...and she tells her friends. Now let's say you groom roughly 30 dogs a week...plus your salary. You do the math. Here's the key to this scheme: You can't slack off on the quality of your work, or you'll lose clients faster than you can reel them in.
As far as benefits, you're at the mercy of your employer. If a grooming shop, vet clinic, or pet supply store offers company benefits to other employees, you might receive benefits in some form as well. On the other hand, if you're self-employed, you'll only receive the benefits you purchase for yourself, such as disability coverage and retirement investments. Of course, you'll still benefit from seeing wonderful dogs every day.