first time trying tdd. which tests should I write?

I'm working on an application for access control on gyms. I want to make all this app testable, but it's my first time with TDD/BDD. I don't exactly know which tests should I create.

Maybe tests from user's perspective? Something like:

• As a visitor, I want to enter gym.


• As a visitor, I want to exit gym.


• As a visitor, I want to enter two times (this should return exception).


• ...


• As administrator, I want to import list of visitors.


• As administrator, I want to clear visitors list.


• As administrator, I want to know who is on the gym.


• ...

Or maybe tests from developer's perspective? Something like:

• testVisitorEnterOnGymReturnTrue()


• testVisitorExitGymReturnTrue()


• testVisitorExitGymBeForeEnteredToGetException()


• testVisitorEnterGymTwoTimesToGetException()


• testAdministratorImportListOfVisitorsReturnTrue()


• testAdministratorClearListOfVisitorsReturnTrue()


• testAdministratorShowWhoIsOnTheGymNowReturnArray()

Which kind of tests should I create before start coding?