Before You Start
If you are going to get into the business of selling auto parts through a catalog, you will have to make it legitimate from the get-go. Decide on a catalog or company name and register yourself as a business with your city and/ or county. Each state and municipality will have their won process for all of this, so visit the appropriate websites, make some calls or go down to city hall yourself to get the proper paperwork. More than likely you will need a business license, a tax ID number (like a social security number for your business), and whatever else might be needed for your specific location.
Your Business Plan
You should never start any kind of business without constructing a thorough and solid business plan. In the case of your auto parts catalog, you will need to decide such things as who your target clientele will be (auto shops, dealers, vintage Mustang owners, etc.), and what sorts of parts you want to sell (your own designs, factory parts, auto accessories, etc.). The idea is to dig deep and get specific. That way, when you feel a little overwhelmed and lost, you can always refer back to your business plan and tackle the next item on your agenda.