First thing you need to do is contact the local or county health department to find out what is necessary to set up a kitchen that will be approved and be able to be licensed. Ask for a copy of the State Code book that details all the minimum standards that you must follow. Use the inspectors as a resource and they will be happy to answer questions. It is much easier to help someone before they get in over their heads that try to help when it is too late.
Then you should contact the building department to find out what codes you have to follow for both building and fire codes.
Get a licensed architect to draw up plans then have them approved by all the appropriate departments.
Then you need to contact your insurance company to determine what type and how much liability insurance you will need.
Determine cost of commercial equipment.
Figure out a price structure.
Figure out costs for supplies.
You might be able to get away without some of the major costs if you can use a commercial kitchen that already has been established. A Church kitchen possibly or a restaurant that opens later in the day or closes early. You might be able to work out a deal where you bake for the Church or restaurant in exchange for the use of their kitchen.
If this is something you really want to do good luck. Also you might even want to look for a bakery that is for sale or one that has gone out of business. That way you may be able to buy a place that has all the equipment you need and already has been approved.