Many physics exam questions I set are meant to be "simple" and "easy", i.e. they aim to test understanding rather than the ability to
-do complicated algebra/calculus
-regurgitate large amounts of information
Hence, always look for a simple way to solve the problem. Never think "It can't be that simple", e.g., just plugging numbers into a single equation or just restating in different terms/words the answer to a previous part of the question.
If your answer involves pages of algebra you are almost certainly on the wrong track...
Try and be neat enough that the examiner can actually understand what you have done. Clearly explain what you are doing, including stating assumptions and results you are using. Don't just write lines of equation.
Don't try and fake derivations.
Include and keep track of physical units in all calculations.
Clearly label axes and scales of all graphs.
Don't waffle. If you don't have an explanation don't make up one by stringing together buzzwords.