I have tutored family friends at different levels throughout their GCSE years to achieve the grades they want

Listening to areas in which the student is aware that improvement is needed is always a great place to start. I would follow this with prepared questions across various areas of the syllabus to identify other areas to work on. Beginning with the areas the students themselves identify, I would then use online textbooks, interactive resources like Seneca learn and past exam papers to cement the knowledge and improve upon what is known.