From memory the big questions are worth 4 or 5 marks, and are all toward the end- fun things like PNRs, ETPs etc.
Do these big mark ones first (and hopefully correctly). After the practice exams youll have an idea on how long each of these take- then allow yourself say 10-15 minutes per each of these. If you don't have the answer, move to the next one. Don't dwell on them if you are stuck, move on and come back little later.
Then work down through the lesser mark questions. It's more likely quicker and easier to discount and guess from a 1-2 mark question. Also, if you guess and get wrong a 5 marker as opposed to a 1-2 marker, the impact to your end result is a lot worse!
That's my tip!