Every hindus must see / listen Sri Vishnu Puran in their mid age to understand Sri Bhagwad. How this universe has been created, Who is the creator, The ultimate secrets & powers of The Lord Vishnu in Satayuga.
Then you can read Sri Bhagwad Gita for the ultimate benefits & to understand what is the purpose of your Life, How your Life & Karma should be, What are the different stages of Life. Hare Krishna.