Visit AP Central's website for the AP English Literature test before the test. This site includes every free response question that has appeared on the AP test since 1999, along with sample responses and detailed explanations of the grading criteria that scorers used for each essay. Best of all, this website is free. Reading over these resources will give you a better idea of what sorts of poems the test uses, what questions it asks and what responses the scorers are looking for.
Study poetic devices and other literary techniques. The free response questions usually ask you to explain the techniques that a poet uses in his work or to evaluate how the poet uses a specific device. If you are clear on the difference between simile and metaphor and can differentiate between an ode and a ballad, you will be able to use these terms correctly in your essay.
Read poetry in books that include commentaries, or find study guides for poems. Try to figure out what the poem means before reading the commentary or study guide, then read the guide and reread the poem to see how the guide's author reached her interpretation. Seeing how others analyze poetry can help you analyze it.
Read the question before reading the poem. This will focus your reading and help you to look for the correct poetic elements. Read the poem at least twice before you begin organizing your essay.
Consider the meaning of the poem. Most poetry essay questions on the AP test ask you to evaluate how a poet uses literary techniques to express his opinion on a topic or to compare and contrast how two poets portray the same subject. Before analyzing the techniques he uses, you need to understand what the poet is trying to say. It is fine if your analysis is a little vague at first; you might find yourself refining it as you study the literary techniques.
Jot down some poetic techniques the author uses on scratch paper. Find a line that particularly jumps out at you and analyze what technique the author used in that line. Continue to look for other examples of different techniques used in the poem. If nothing jumps out at you, think of literary devices and start looking through the poems for those. Poems on the AP test rarely have rhyme or rhythm, so look for figurative language, allusion or symbolism.
If the question asks you to compare and contrast two poems, see if the poets use the same techniques. It may be that they both favor one technique, but use it in different ways, or it may be that they use entirely different techniques. Either is a valid subject for your essay. You can compare and contrast poems that personify love in two different ways just as easily as you can compare and contrast a poem that leans heavily on simile and metaphor with one that does not use any figurative language at all.
Organize your notes into an outline. For an analysis of one poem, you can either go through the poem line-by-line describing the poetic elements or give each literary technique its own paragraph. For a compare-contrast essay, you can either tell how the poems are similar and then tell how they are different or begin with an analysis of one poem and move onto an analysis of the next. If any of your notes do not seem to fit anywhere, do not include them in your final essay.
Write your essay. In the first paragraph, give your interpretation of the poem or your opinion on the most crucial similarities and differences between the two poems. In each body paragraph, explain how the poet's techniques support your interpretation. In the final paragraph, restate your interpretation in a different way and summarize the evidence that you gave in the body paragraphs.