Ok, start with making your concepts of different subjects clear, no matter how long that takes you. When I was at this time I used to study for 6-7 hours daily apart from coaching Online or offline. So don't start shooting for JEE-advanced start and focus on your concepts more.
First of all Congratulations Mr.Venkatesan in completing 10th standard.
It dependes on the caliber and level of the student.
If you have good memory and strong understanding of concepts then you would need daily 4 to 5 hours of practise in all subjects where you can plan and divide number of hours for each subject preparation.
If you are a hard working person not that good enough with memory and understanding concepts ( I mean depending on someone to make understand the concepts well) then more practise time may be 6 to 8 hours of practise required daily.
what ever the level of student, for each subject from the begining
i) Daily revise the taught concepts well
ii)Try to make your own notes, topic and chapter wise
iii) Note of techniques and short cuts.
iv) Daily practise on learnt concepts of each subject minimum 1 to 1.5 hours
v) Exam practise to understand time sence .
vi) From exam practise try to know the difficult areas that you couldn't perform well and focus on those areas and be perfect.