A friendship poem is one of the best gifts you can give your friend. It costs next to nothing, but the emotions and heartfelt effort involved are without a price. Poetry isn't easy to compose, and you may need to work at it in order to achieve the precise effect you wish. If it springs from an honest place, however--with the qualities of your friend foremost in your mind--then it can't help but reflect the good feelings you carry for him.
Think about the qualities of your friend which you'd like to expound upon in your poem. Traditionally, poems of this sort focus on physical qualities, but you can focus on whatever you want--dependability, intelligence, sense of fun, passions and anything else which comes to mind.
Catalyze your feelings about your friend into a series of words and phrases. These will be the building blocks of your poem, on which you will base the entire structure. You may wish to select your words with the poem's rhyme or meter in mind, but it's not necessary.
Determine the meter and structure of your poem. You can select from an existing type of poem to help organize it (such as sonnet or haiku), or adopt a free verse poem. Familiarize yourself with the lines, inflections and syllables used in your chosen type, and begin musing on how your chosen words can be placed in it.
Plan out the use of poetic devices such as rhyming schemes, alliteration and repetition. They aid with the structure of the poem. Make sure you don't overwhelm the underlying emotions with them, or else your poem will feel too mechanistic.
Write out a draft of your poem, focusing on the decisions you made in Steps 2, 3, and 4. Don't worry about making it perfect right away. Just get it all down on paper in a recognizable form.
Revise and edit your poem, polishing any rough patches until you're satisfied with the results. If you have someone you trust, you may wish to let him read the poem and make helpful suggestions.
Present your poem to your friend, and watch her while she reads it.