Choose a subject you’re truly passionate about. Investigate the courses at both Oxford and Cambridge so you know how they differ and the specifics of each. Each university offers different subjects and combinations of subjects. For example, Cambridge offers a broad Natural Sciences course which is great for those who like Science but are unsure exactly what to study, while at Oxford you would need to choose between Chemistry and Physics. You may be able to combine a second subject with History, Philosophy or Classics, for example — with the advantage that an unusual course should be less over-subscribed.