I think it's by having immaculate looking hands.
Oh, but you can still aspire. The bar has been lowered. Nowadays, you only need to be a right hand index finger actor. (Or did you miss the agency casting notice? They might even greenscreen and horizontal flip-flop for the left right hand, I mean, the right left hand.)
Notice how in the early iPhone commercials, the hand struggled valiantly to hold the iPhone stock still - but in the most recent three commercials, the hand holding the phone's bezel has become a still stock image? So many fewer takes! So much less to manicure! Perhaps the model, or the model's left forearm, met a grizzly end. But the left hand shall never age! The left hand shall live...
forever!
Either way, it appears the left hand no longer has any idea what the right hand is doing. Can't even be sure which right finger it is, seeing as the iPhone pretty much flips off all of Apple's competitors. Also looks like they may just animate the obligatory "taking a call" money shot at the end - you know, the customary "wiperblade," with a bit of "shimmy" just beforehand. Ugh, I mean, before.