Read the poem aloud at least once, as well as multiple times to yourself. You do not have to memorize a poem to write convincingly about it, but you should know it fairly thoroughly.
Decide what you think the poem is about. If you are absolutely mystified, consider writing a paraphrase, which is a line-by-line "translation" of the poem into plain language. Once you've made a general decision about the poem's meaning, write it down so you can refer to it as you look at the details of the poem.
Pay special attention to unusual words. It is often helpful to ask yourself what the most important word in a line, couplet or stanza is. You can also look for words with unusual connotations. Make a note of these, especially if the word suggests something that you didn't expect to see.
Identify examples of poetic devices. In the margins, simply make notes of the kinds of poetic devices you find. Don't worry about explaining them yet. Keep a list of poetic devices handy. If your instructor has emphasized certain devices above others, such as metaphor and imagery, put those at the top of the list.
Mark lines that most directly reveal the meaning of the poem. These lines will probably be most useful in supporting your thesis. Place a different mark by the lines that remain confusing or mysterious. Return to these lines last.
Write down your thesis and support your interpretation of the poem by explaining the lines you marked. Be sure to mention not only what the lines mean but also how the specific language helps to express that meaning.
Return to the lines that confused you. Decide how you can make them fit your interpretation of the poem's meaning. Be creative with this part, and don't be afraid of coming up with an outlandish idea. If you think there is no way to make these lines fit the poem, consider adjusting your interpretation of the lines.
Explain how examples of poetic devices emphasize the details and meaning of the poem.