Read Alice Notley's work aloud. Most poetry is best understood when read aloud, and Notley's poetry is no exception. Reading aloud can often help you to hear nuances of language and to understand when a speaker changes or when particular words or phrases receive more emphasis. Pennsound, an audio poetry collection from Penn State University, has many archived audio files of Notley reading her own work which can help you to follow and better understand her poetry.
Determine which era of Notley's work you are reading. Alice Notley's career has been long and varied, so it's important to understand the different aims of her work during different time periods. Notley was originally associated with the second generation of New York School poets. New York School poets are often identified by their use of humor, irony and interest in working urban life into their poetry. Notley's early works, particularly poems that appeared in works from 1971 through 1980, largely follow this pattern. These poems are often about daily life in the city and her relationships to her children. Throughout the 80s, Notley began to shift her focus to larger social issues, such as feminism and politics, as in her poems "Disobedience" and "Descent of Alette."
Note the type of poetry you are reading. Notley has written short, lyrical pieces, but also long narrative works. Her poem "Descent of Alette" is a long narrative poem, meaning that it tells one continuous story. When reading this kind of poem, keep in mind the overall plot, movement of characters and shifts in setting. Many of her poems from the book "Mysteries of Small Houses," on the other hand, are lyric poems, meaning that they are mostly short and cover a specific experience or moment in time. These poems should generally be understood separately, as a specific emotion or experience. Most of Notley's poems, whether lyric or narrative, use a "stream of consciousness" form, which gives reader access to direct thoughts of the narrator as they happen.
Review basic poetic terms in order to familiarize yourself with general poetic methods. The Academy of American Poets Poetry 101 page provides some excellent resources for understanding general poetry terms and methods.