Another point is to be realistic regarding the initial capitol outlay. For every additional area you wish to add you will have additional expenditure. Some types of offerings dovetail with others where you can use equipment or space at different times and increase profitability. Others will require separate expensive equipment, or training. A new business can take a while to get off the ground. You want to have enough money to get through the lean months as you build the business and figure out what advertising and retention strategies work for you.
And when you do your mission statement and philosophy make sure you have done your market research carefully, and leave room in your calculations for mistakes. I know of one place that sunk a lot of money into Pilates equipment but was not able to hire more than one certified person to train people on it…. and discovered that the particular population they were serving were extremely unwilling to pay for those services.
The best advice I ever got when I was preparing to start my own business years ago was: ‘Dig deep, not wide’.
As you get successful you can always add on, (though it is useful to have a a plan at the beginning as to where you would add on so that you can build toward that, rather than having to do major tear downs.)