Choose a Setting
Gothic poets like Byron, Coleridge and Keats examined the dark side of the human condition, so your themes should reflect this emphasis, too. You can create a mood that draws the reader's attention, and establish a double meaning for him to ponder. For example, you can use churches, graveyards and ruins to suggest confrontations with such infinite forces as death, spirits and time. Exotic locations, such as castles and haunted houses, also work well as a method of symbolizing your narrator's unsettled inner psyche.
Decide on a Theme
Your chosen settings will affect your theme, which is the writer's message. Unlike other literary genres, Gothic poetry favors the emotional and supernatural over the rational world. Narrators who struggle with repressed sexual desires are common, as well as characters who question their own sanity -- such as Coleridge's Ancient Mariner, for example. Angels, demons and ghosts are key devices to explore inner conflicts. If necessary, study other Gothic writers, like Byron, to see which approach works best.
Double-Check Your Dictionary
A Gothic poem is only as good as the words that you select. Every major word or phrase must appeal to the reader's sense of sight, sound and smell, such as your impressions of walking through a forest on a moonlit night, according to the Gothic Portal website. For best results, you'll want to choose words that convey multiple meanings, so you'll want to keep a dictionary -- and a thesaurus -- handy. Read your work aloud, which helps you avoid too many similar-sounding words that will dilute your poem's impact.
Every Gothic poem needs a strong title, preferably one that gives the reader a clear idea of its subject matter. For best results, the Gothic Portal recommends keeping your titles at four words. Also, try to end your poem with a twist that gives readers something to think about. Most importantly, as Sorrow Man's website advises, don't let stereotypical fears of writing about emotionally painful subjects, like death or suicide, deter you from expressing yourself in those areas. For that reason, you may not want anyone to see your poem until it's completed.