hey, so for a Yeats essay, you NEED critiques since it's a critical study, it's a good thing to know about Yeats' context cause that'll help you with talking about the poems seeing as he put alot of his life into his poems, obviously, you'll need to know all the poems so you can use quotes and identify the techniques used within the poems. Also come up with a concept table of possible arguments you could use in the exam and using the concepts you like, start coming up with an evidence table including everything you could use to help argue your point, this includes techniques, quotes, critics and make sure you have your own personal opinion and don't form it just from critics, the rubric asks for your opinion.
An example of a concept could be 'Yeats’ poetry reflects controversial ideas of religion and spiritualism', so arguing the values and morals that are reflected in Yeats' poetry is always a good thing to do, cause then you can be broad in your argument and interpret the poems how you want.
http://www.sparknotes.com/poetry/yeats
There's a website that can help you out in interpreting Yeats and his poetry a bit more.
Hope I've helped!
Good Luck! x