If animals are your passion — the field that makes you want to get up and do something — then you can certainly achieve this balance. Most employers prefer candidates to have previous experience taking care of pets. She uses a site called Tailster to find clients. Veterinary assistants help veterinarians with basic office tasks iStock. This is more of a serious business idea than the other side hustles on this list, so it will probably require some upfront investment in your tools and supplies. You can easily find clients by starting locally. Those who work in states such as Minnesota, New York, and California can make the most money.