Leo Tolstoy is usually known for one thing: writing extremely long books. With that being said, it depends on how much time you have and how committed you are to finishing the book. My advice is for you to start with The Death of Ivan Ilyich. read more
The first writings from Tolstoy I read where short stories, such as "The Young Tsar", "Alyosha the Pot", "Memoirs from a Madman" (not to be confounded with Flaubert's), and "After the Dance". I got used to Tolstoy's writing, which was a good thing. read more