<p>Probably do well on your APs or IBs as those tests will be the basis of your conditional offer should you do well on your interviews (Oxford and Cambridge).</p>
<p>Take all the APs or IBs for the subject you are interested in studying.</p>
<p>For Cambridge, you’ll need to take the STEP exam if you are planning to study mathematics.</p>
<p>At Oxford you have to take some easier form of an entrance exam, (still hard though), but those tests normally follow after you have received an offer, so they’ll tell you.</p>
<p>Most important thing is to do well in all the classes related to your desired subject to get an interview, then do very well on your interview to get offer.</p>
<p>Curious… what subject are you planning to study?</p>