menu – What would users feel comfortable to see first in navigation

Reading about object-oriented UX and audience based navigation, I still not sure how to approach the following problem:

  • I am building a careers section of a web site, where I must present job/internship/training opportunities by location and by profession. I am intuitively going for profession first – that is, on the first screen, users would see boxes with professions (this is the so called audience based navigation). Once a user identifies with a profession and clicks on the respective box, they would see boxes for jobs/internships/trainings. Once they choose any of those, locations would show.

Is this the correct order of presenting the navigation choices? How could I possibly know what do users care about first among those three?