These days, pet sitting is a flourishing business. Our society as a whole is more mobile than ever, which creates great opportunity for this business. A lot of folks choose for one reason or another that they wish to get involved in pet sitting. Even so, as soon as they find out what work it requires they back off a bit. Bottom line - you need to come up with a person who has been in this business for a long time.
Once you have a few names, contact some of them and have them visit your home. See how they interact with your pet, and how your pet reacts to them. Animals have a great instinct and "sixth sense" about people.
Ask the tough questions. Ask the pet sitter why you ought to hire them and not someone else. They will in all probability say, "Because I LOVE animals!!" This is a reasonable answer, but my four year old niece also loves animals. I don't think you would trust her to watch over your pet while you are away.
You need to find out what sort of background and experience this individual has with animals. Do they understand how to pick out signs of sickness? Can the tell the difference between a healthy pet and one that is hurting? Do they know the right steps to take in case of an emergency? Having an affection for animals is an admirable trait but it really requires more skills and experience than that alone.
Some questions you should ask before hiring a sitter include:
How many times will they visit your pet each day?
What services will they perform in your home? Feeding and providing water is obvious, but what about playing with the pets or walking with them outside (if it is a dog). If the pet's stomach is upset and it vomits, will they take care of removing the mess?
Take your time and be diligent in choosing your pet sitter. The time and trouble you spend now will pay off in peace of mind and reassurance up the line.