There are many things you will need to do to start your pet sitting/dog walking business. These links will help get you started.
One of the first things you will need is an Employer Identification Number (EIN#) which you can apply for from the federal government. You will need this for many government forms, employee paperwork (if you use employees), your income tax schedule C. If you have your business set up as a DBA then you are not required to get an EIN# if you do an LLC then you are required to get an EIN#.
You will need to collect sales tax in most states, here is a link to all 50 states sales tax websites. Some states do not have sales tax, some states don't require certain services to collect sales tax, there could be additional county/city sales tax so you need to check the jurisdictions you service carefully.
Business insurance is important to protect you and your business, you don't know when an accident can happen. There are several companies that offer business insurance specific to pet sitting/dog walking. Things I my colleagues have had happen to them: employee drove through clients garage door by accident, employee forgot to close the front door when unleashing dog and they bolted out the front door and got lost.
Joining a professional organization will make you look more professional, some have member benefits, and keep you up to date on pet care information. Several have a pet sitter locators where your business is listed and potential clients can find you.Here is a list of the pet sitting organizations.
Having a pet sitting software will make your business more efficient, clients can have their own portal for booking requests, all client and pet information is saved in the software which can be accessed from a mobile device, all sits/walks are stored in the calendar so you don't miss a visit to a pet. There are lots of different software out there, here is a link to a list of the pet sitting software.
Make sure you are getting all the deductions you are allowed for your business expenses on your income taxes. You will want to consult with a tax accountant, which is deductible, but here is a link so you know what to start keeping track of for tax deductions
If you hire employees you will need to do a background check on them. A colleague of mine started a background check company for pet sitters Pet Pro Check. They have a fast turnaround time and do a thorough job.
Taking a pet first aid class is important to learn how to deal with emergency situations with pets, how to diagnose potential health problems and more. This will also put many potential clients at ease. When I first started I took an online course that was cheaper but have since taken several classroom courses which I liked better because it was hands on training. Pet Tech is one of the better courses that was recommended to me and I was very pleased with the instructor I had each time.