The new specification has a real emphasis on problem solving, not just doing easy problems. If you want to improve your problem solving, you may want to look into Intermediate maths challenge papers, although they don't really touch upon actual GCSE content, but they really do improve your problem solving skills. In this new syllabus, we will no longer be asked the generic questions that were asked almost every year in the previous specification. It requires thinking out of the box, to a certain extent, and applying what you learn.
This is coming from someone predicted a grade 9, who has not achieved anything lower than 75 out of 80 in any practice papers.
As for how to get the 9, I don't really have much advice apart from for you to practice, as I can practically remember everything that I have been taught and revision for me mainly consists of reviewing concepts that I haven't touched upon in a while; not rigorous practice.