Definitely be present when central lines & a-lines are being inserted. Get to know what items you'll need to set up, etc.
If a patient has a pacemaker, get acquainted with it too & learn the different modes & underlying rhythms.
Get familiar with vasoactive drips, their rationale, side effects, etc.
Ask the nurse & respiratory therapist modes of ventilation & why, weaning from the vent, etc.
Try to be present when intubations occur.
And definitely if there's a code, soak it all in!
And if you have any questions about anything (which you will!) ask, ask, ask!
Hope this helps!!