I am only an undergrad looking for a summer job, and in my current apartment, they don't allow pets. By per night, does it mean you stay over the persons house to watch over the dog. Or can you just go over whenever you can to walk the dog, fill it's bowl, etc.?
I do something called "potty relief". I go once in the a.m. spend anywhere from 30min to an hour and then the same again in the p.m. I bring in the mail, water plants, feed the cat, clean up poop and walk/play with the pup. Anything else the customer needs.
If you go to a persons house to care for their pet, that's called being a "traveling" sitter. I provide that as a service as well, and I usually talk with the owner to understand their expectations. Some owners want you to stay over because their pet needs it, some are fine with drop-ins throughout the day.
As a "traveling sitter", it is especially important to find out what the pet-parent's expectations are. Keep in mind there might be other people periodically coming & going (maids/family/neighbors) and doggy check-in remote cameras. My experience is that most pet-parents want to keep their dog(s) on the same routine - with walks in their neighborhood and meals served at the same times as usual, sometimes asking you to agree to be there within specified half hour time ranges and provide photos during visit.
If you are sitting a dog in his own home there are a lot of things to talk to the owners about at the meet and greet. The y need to have their needs met and you have a life also. It takes a lot of conversation.