To write an "In loving memory" poem, read examples of others and collect memorial verses that relate to the deceased. Use this material to write drafts of the poem.
Memorial poems don't have to follow a specific format. However, they typically describe a person and include memorial quotes.
To write a poem about a person, WritersDigest.com suggests starting by writing a description of that person. Next, add to that description by concentrating on the deceased. Find new ways to describe the person. Use literary devices such as metaphors and imagery.
After that, start writing a first draft. Write two or three stanzas incorporating the description of the deceased. As the editing process begins, pay attention to structure. Poems don't have to rhyme, but they are meant to be read aloud. Use line breaks to create an unusual pause for emphasis.
Start incorporating memorial verses into the poem. Memorial verses can come from other memorial poems, religious proverbs or Bible verses. For example, an Inuit proverb compares deceased loved ones to stars. Such verses can be paraphrased, or they can be used to start a poem.
Finally, edit the poem for brevity. The goal of poetry is to convey as much as possible in the fewest possible words. Finish the poem with an uplifting thought about the deceased.