I would use the time to understand what is being asked and then plan which questions to answer first. So that I am not taken by surprise when I bump into a difficult question and might as well spent that time answering another question that could have been a better pick for the time available.
I would normally jot down points that come to mind and underline important parts to question while reading. This could range from an acronym for definition questions, starting a derivation question, draw out a box to be filled out (e.g for chi-squared question), placing question marks beside something that looks different/tough.
