No infallible advice can be given on how to write a poem, because poets develop their own approaches in time. Nonetheless, here are a few exercises to generate the raw copy.
1. Plan. Ask yourself:
How much time is available? Opening lines can be dashed off in minutes but completion may take days or weeks. Be cautious, and aim perhaps for 5-10 lines in an evening. Don't wait for the muse, but write what you can when you can. Odd phrases and lines are at least something to work from, and more inspiring than a blank page.
When you write letters or tell stories, do you usually start from a newspaper article you've read, an anecdote told or overheard, something witnessed, a general reflection? Start a poem in the way you're most comfortable with.
What sort of poem had you in mind? A story, a comment, a tribute, a protest, an elegy, a character study, a memorial? Skim through contemporary examples to start yourself off.
About the issues involved. Imagine the poem were a newspaper article: what points would you make, with what evidence and resounding arguments? Got it together? Go on then: let yourself go. Something will emerge.
2. Make sure the subject's important to you. Death of a friend or family member, rites of passage, the bitter sweetness of first love, one of life's turning points, old transgressions, a childhood incident, injustices, unacknowledged fears... Use a mask of the second or third person if the content is too personal or painful.
3. Give yourself up to reverie. Go for a walk, lie on the sofa and close your eyes, go to bed, cut out the surrounding world. Jot down the things that come you, in whatever order or confusion. Put the scribblings away for the present, and only open the folder hours or weeks later to see what you've got. You'll be amazed at what's inside you.
4. Free the imagination. Try:
Automatic writing. Say 5 minutes at a stretch, continuously, never stopping. Go through the material when you've collected in ten pages or so, and circle anything interesting.
Get a friend to say words at random. Write down the first response that comes to you. Build a poem around three of the words.
Open a diary or journal (yours or someone else's) and jot down the first incident on three successive pages. Make a poem of these.
Describe, as closely as you can, some recurring dream or nightmare. Reverse the sequence, and then make a poem.
5. Work through metaphors. Take four lines of any contemporary poem. Identify the metaphors. Then use a thesaurus to find alternatives for the metaphors. Then repeat with the alternatives, finding words even further removed from the originals. Think deeply on three or so of the more interesting words, and see if can draft a poem incorporating them.
6. Write a pastiche. Take a stanza of something well known and rewrite it so that a) the idiom is entirely different, b) the lines end with nonsense rhymes, c) the piece is ruined with the smallest possible change, d) the piece looks completely fresh and contemporary.
7. Take the last line of one of your poems (which needn't be good). Carry on from there, ignoring entirely what you drafted before.
8. Repeat some of these exercises on material swopped with a fellow student or poet.