first of all, best of luck for your preperations and exams
you should start with residential status and other basic concepts.
Then move towards heads of income Salary, then House Proiperty, then PGBP, then Capital Gains and then Other Sources.
then go for Deductions.
after that, you should try to attempt the questions for total income.
and then go for other remaining topics.
to remember the sections, you should read them in sequence and keep on remembering it and evaluate yourself by checking any of sections while you are not studying.