Study some examples of different literary time periods. Each time period has certain characteristics in its literature that make it easy to identify.
Look at the culture of the literary time periods. Works of fiction will closely represent the people and society of the times. There will be political as well as social references throughout that make it hard to distinguish between fact and fiction.
Analyze the different literary types used in each time period. Shakespeare and his contemporaries wrote mostly in verse and play form. American poets like Whitman broke out of definite rhyme and meter patterns in free verse poetry. Modern poets tend to be more abstract in thought and idea.
Consider the differences in vocabulary and how language changes over time. Different time periods have different word usage that can make understanding the literature of that era more difficult. To speak intelligently about literature, one must have some knowledge about the how language evolves.
Think about the differences in subject matter during different literary eras. What was taboo to write and speak about a hundred years ago is commonplace in modern literature.
Work on looking closely at the characters in literary novels. They will be many layers and dimensions, both in life experiences and in their relationships with those around them. Most characters will have their own plot lines that parallel the overall plot of the story.