Turn the maths you know into marks on the paper.
Two students can know the same maths and finish two grades apart. The difference is technique: how they read the question, lay out working, handle rounding, use the calculator, and spend ninety minutes. None of it is taught as a topic. All of it is marked.

The GCSE Maths Exam Technique Workbook teaches it in ten short sections, each with an exercise you mark yourself against a real mark allocation, the way an examiner would.

Ten sections and nine exercises on turning known maths into marks, with full answers and mark allocations.