Just the thought of starting a practice, or even taking over an existing practice can be mind-boggling. There's so much to do! And they don't teach you how to do it in dental school. This is your first rude awakening to the fact that you're not just a healthcare provider, you're a business man or woman.
Don't panic, it's been done before. First, make sure you locate a facility, or the space for one, that is in a good location with ample parking and great visibility. If you're building from the ground up, think longer term. I don't think I've ever met a dentist who felt that he'd given himself enough square footage. You'll probably need more room for storage than you think you will. You may want to add a second hygienist after a while and you may really appreciate having an overflow room. A dedicated consult room is a plus, as well as a separate bathroom for the patients and staff. Make sure you use a builder who has experience designing dental offices and who will higher subcontractors who do, too, especially when it comes to plumbing. On the other hand, don't go crazy with space, or too many specialized "areas." I know one dentist who has an enormous office different stations for everything you can think of and a lot of it is unused. It's also miserable to scrounge for room to stock supplies, or to have stress caused by patients waiting until rooms can be cleaned to seat them. Think about how you'll want to practice and then fit your office to that concept.
If you're buying an existing practice, make sure you know what you're getting. How old is everything? Really look at the walls, the carpet,the window coverings. How old are the computers and the server and what version of any practice management software will they support? Is there digital x-ray, how old are the sensors? Check the upholstery on the dental chairs, is it starting to crack and show wear? Replacing these things can be expensive and it hurts to do it soon after you've made the big leap into practice ownership. How much stock of supplies will be left on hand when the transition takes place? Make that part of the agreement. How will outstanding collections be handled, who will handle it? When will the patients be told about the transition? Will the seller stay on for a period of time? Take pictures of what is in the office, I've seen a dentist's wife come in and swap out staplers, phones, adding machines, you name it.