I would take a course in running a small business. Not everyone is a great photographer and a great businessman.
Do you plan on opening a studio or working out of your home. If working from home make sure your zoning ordinances allow it. All you need is one upset customer to rat you out to the zoning board who could find you and/or close you down down.
You'll need a business license, commercial insurance, a web or Facebook presence, business contracts, etc.
Have you decided on a genre? Will you do weddings/engagements, graduation, real estate, children/pets...?
Do you have all the equipment you need? Backdrops, lighting, wardrobe, spare parts for said equipment?
Do you, can you afford an assistant? They are just as important as everything else so you don't have to kill yourself by dragging all the equipment to and from the location as well as setup and teardown.
I suggest you take a few small business courses to make sure you can go it alone.
It won't be easy starting up your business. Have you thought of doing this part time until you build up your clientele?
What about wardrobe? You can take a female friend with you to thrift shops and second hand stores to buy clothes. You'll need a clothing rack and hangers for the wardrobe and someone to launder them regularly otherwise your clients will smell the stale order and refuse to use them. Many of your clients may want to use their own clothes.
If you do swimsuit shoots you'll need a female assistant and a few full length robes for the women to wear during pauses in the shoot. Make sure she brings along a female friend or family member to help with wardrobe change. That said if you have a studio make sure the change room is clean has a single full length mirror, chairs, hooks to hang clothes, and a good lock for the door.
Make sure they know that all images belong to you. Make sure you copyright all the images you take. If they'd like additional copies you can sell them. Oh and hire a good lawyer.
