You need to be clear: is this a hobby or a business? And if it's a business, do you have people coming to your home for portrait photos and the like? If you plan to treat this as a business, you may need to consider zoning issues (if you'll have people coming to your home).
While you may not have special licensing issues (forming a corporation or LLC may be enough to get you started legally), you will want to speak to an attorney about contract issues to make sure that your customers pay you timely. Also speak to your accountant about setting up a proper set of books to account for your business income and expenses.