(a) cover ALL the relevant poetic devices (including the form of the poem and, if applicable, how  that form contributes to how the poem works) 
(b) explain and show accurately, with textual analysis, what is happening in the poem and how it happens
Do not provide a formal introduction and a thesis statement placed at the beginning — just jump right in and explicate the poem. State your thesis in your conclusion. This way you will have argued towards your conclusion/thesis.