Syd - Mel Gear down, maintenance ferry flight is a common question. Also think about failed gear retraction, subsequent hold to burn fuel and return to land type questions.
Get a pack of multi coloured highlighters and every time you do a practice question use a different colour on that route. There are only so many city pairs that they can use and you will see similar ones in the exam to the AFT practice questions.
My advise on order of questions is to start with two 1 mark questions to calm the nerves, then do a big question, then to rest the brain come back to another 1 mark, then back to the another big one and so on.
I have taught this front/back method of attempting the questions for a while and it seems to work for most people. As it helps to stop you getting bogged down in the big ones if you try them first or running out of time if you leave them until last.
The best piece of advice is to develop a process and use it the same way for every practice question you do. Be very neat and write all the numbers down as you go on your flight plan, even for the 1 markers do a line on the flight plan. If you try to do it all on the calculator and your answer doesn't match theirs then you have nothing to check or go over if you haven’t neatly written it all down. You have pages of flight plans so use them!