I have finished my high school in China and come to Singapore study for O-Level for 1 year,so I have the good understanding of math and combine science(physic and chemistry).In the past,I was teaching my friend's friend math,I could obviously see there is the leap of progress.I would focus on students' foundation,and guide him/her step by step in order to let the student know the logic behind it,so that the students are able to solve the question by their own with the strong basic knowledge.
I am able to start on next year onward.
I think 2 hours is enough for one time as if it is a long duration I think the students won't be able to pick up as much as he can.