Allocate sufficient time for each section. Personally I allocated 35 minutes for each long question and 40 minutes for section A. ALWAYS adhere to the time allowance and if you have time remaining at the end you can return to a question. Attempt to garner as much marks as possible from each question, not full marks on one question to the detriment of the others.
When preparing section B focus on the four topics which you intend on choosing on the day, for example orthographic, axonometric, transformation geometry and conics etc. And also practise an extra topic just in case one of the topics which you were intent on doing doesn't appeal to you on the day.
In addition I would genuinely recommend practising exam questions, especially the short questions. For instance for the mocks I failed to revise sufficiently for section A and focused on section B. Consequently I got a B in the paper due to the fact I completely Neglected the short questions when studying.
However for the actual exam I focused on both sections and obtained an A in the exam. Essentially don't primarily focus on section B, as section A can truly determine your grade.