Perfect Duluth Day

Dog and House Sitting

I have been taking care of critters and their homes for about 7-8 years here in Duluth while their owners are on vacation and such and was recently thinking of making up fliers and business cards. Would I have to “register” or something as a business owner? Is there a certain amount of money you need to make to have to pay taxes? I just don’t want to do something illegal by accident. Any help appreciated.