If you use a system like mind-body it can help measure retention.
Before you worry about retention you need to establish clientele, to get people through the door. With any new business that can be hard, especially with something like yoga where word of mouth is the number one way to get students in the first place.
There are quite a few things that affect retention.
Location makes a difference. In an urban center where a lot of people work on contract, or near a military base, or a college town, you may find that people will come and go for reasons that have nothing to do with your studio. Say you open in a town with a business that employs almost a third of the population. If that business has a problem, so will you. If you are in a upper socio economic area with a population with a lot of money for non essentials it may be less of an issue, but of course, to open in an area like that the rents will be higher, and you still need enough money to carry you through the lean times as you start up the business.
A well designed studio helps. An easy to find address, good parking, or near mass transit. Lighting, flooring, heat“. all those things can help.
Smart use of things like Facebook, email, and other methods of keeping people aware of your presence.
But yes, you can have a location with lots of problems and a good teacher can keep students, and you can have the most beautiful studio in the world, and if people do not mesh with the type of yoga or teaching methods of your teachers it will not matter. If I were opening my own space I would opt to spend more on teacher pay than on candles and pillows. And I would spend more time looking for teachers, and training them, than on interior design. (though I would do that too)