Although facing an unseen poem can seem daunting, reading a poem with a fresh eye allows you the opportunity to really allow certain lines and themes of the text jump out at you and give you ideas. When approaching the ELAT, you'll want to read through all the texts briefly, and then quickly choose two which you can compare and contrast in an interesting way. Try not to choose two which are too similar, but two which have contrasting takes on a theme, or are different in style or form.
When planning your essay, if you're focusing on one or more poems, focus on the texts by considering form, style, rhyme, the subject and voice of the poem, and structure. For instance, what is the overall message of the poem? How do the different structural aspects of the poem feed into that? Then look at language - imagery, metaphor, and other literary techniques. Through your analysis, consider why the writers have made these decisions and what they are trying to achieve. When structuring your essay, make sure you have an overarching idea about how the poems/texts which you have chosen are functioning in similar and/or different ways, and then piece together, point by point, the different ways in which the texts do this.