I studied geography at GCSE and A level and received grades of 8 and A* respectively, as far as experience goes.
Lessons would be delivered online but completely informal, call me whatever you like and tell me what you hope to get out of lessons and what you want to improve on, and things can be tailored from there.
Things won't just be PowerPoints like in school, knowing exactly what you want to improve on is the most important thing and so lessons should be different to school, especially if you're already struggling with something, doing it the same as school teachers won't help!
I can tell you the approach needed for exams and the questions in them, as well letting you know how much emphasis to place on certain aspects of the subject.