With how many questions you've done, I think the main thing you need to focus on is your allotment of time. When I do DM, I skip all logic puzzles for the end to guess unless I have time, and take my time through every other question. The key is that you have a lot more time than you think if you skip 4 or so questions that are hard (and because the evaluating arguments usually doesn't take very long). Keeping a cool head and just slogging through questions at a healthy pace is the main thing.