LLC or corporation is usually the choice. You should read up on that or ask a lawyer or accountant. You can do it yourself most likely, but hard to navigate in my opinion the first time dealing with it. LLC usually is less expensive than a corporation, but not necessarily.
DBA is what your businesses is known as. For example you might have a corporation filed with your state as Princess, Inc. or an LLC called Princess, LLC. One or the other. However, on your store front the sign might say IP Photography, and that’s what your customers call your business. You Do Business As (DBA) IP Photography.
The reason this is good is because if you ever sell the business it’s common to close the corporation or LLC and only sell the DBA and what is related to the DBA, like the website, client list, equipment, and so on. Or, you might keep the LLC intact, but still sell the company with the DBA if you have several businesses under the one LLC.