Firstly, I would recommend reading the piece of poetry out loud to yourself and ask yourself the following questions; are there any lines or phrases that stand out to you? Are there any phrases or words that you find yourself placing more emphasis on? What about the speed of the poem? Is it fast or slow, or does it change?
Secondly, I would grab a highlighter and highlight all the bits of the poem that you find interesting. Then look closely at them, how do you think the effect has been created? Are there any letters or sounds repeated? Can you work out the rhyme scheme? Any adjectives or imagery that you find striking?
However, examiners or essay markers are not interested in a checklist of literary techniques. They want to see that you can use the relevant evidence to back up your argument. You may see ten literary techniques in an extract but only use five or six in your answer.