Write a list of the information you need to know in order to write the poem. For example, who is it for, what kind of poem (i.e. love, marriage, death), is it for a special occasion, are there any special requests.
Ask the person (you are writing for) what their thoughts about the poem are. What are they looking for? What do they want to express? How do they want it written?
Imagine yourself as that person and write in that voice. If you are writing a poem as a gift, you can write it in any voice you like but, if you are writing for someone else to give as a gift, you have to imagine you are that person. This will help personalize the poem and make it more suitable for the reason/occasion it is being written for.
Edit your poem. Re-read your poem and make changes where necessary.
Edit again. Have the person you are writing the poem for take a look at the draft and make changes where necessary. This is a great time to go over the information you gathered in step 1.
Finalize and present your poem in a professional manner.