The first 10 or so questions on the paper are 'easier' in that they are normally just one topic, not the hardest topics, and mostly just one step. Getting as many marks as possible in this segment of the paper is key to achieving your target grade.
The next 8 or so questions are generally a bit harder - maybe two steps, the less straightforward topics and maybe worded problems or deliberately disguised questions.
Then there are the final 6-7 questions which are typically the nasty ones, complex and muti-topic questions that require some lateral thinking just to get started.
Higher tier, calculators allowed.