Avoid the pathetic fallacy
Pathetic fallacy is defined as endowing non-human things with human qualities. Birds sigh; clouds weep; trees pray; rocks sweat. These are twee ideas, no matter who writes them. (Theodore Roethke, a poet with a high position in the American canon, used the “sighing bird” image.) Worse, whoever uses the pathetic fallacy disrespects the thingness of things, the animal vitality of animals.
Avoid inversions grammatical
New poets sometimes invert the natural word order of a sentence or a phrase because they think it sounds “poetic” or because they need to do so to keep to a rhyme scheme. The technique almost always sounds precious and old-fashioned. However, there are times when an experienced poet may profitably invert grammar in order to emphasize the object of the sentence or achieve a certain effect.
Show it to me, baby, show it to me
The saying “Show, don’t tell” has become a truism yet it hath truth. To blurt out “what you mean” or “how you felt” only waters down your poem for the reader, whom you have just robbed of the opportunity to experience something with you. Instead, you’ve offered only a lesson or a lecture or a dubious self-display. Trust your material! If you’ve chosen your subject well, and rendered it faithfully, your poem will “mean” so much more than if you stated things outright. You may even surprise yourself.
If you rhyme, make it new
Have you just rhymed tears with fears, moon with June? So has every bad poet from here to Tin Pan Alley.
Get thee to a library
Bone up on prosody, defined as the study of poetic meter and versification. Good resources: All the Fun’s In How You Say A Thing by Timothy Steele; A Book of Forms by Lewis Turco. Read all the poetry you can get your hands on, individual collections, Selecteds, Collecteds, anthologies. Read the contemporaries and read the canon. In combing through the anthologies, you will find certain poets who speak to your soul. Get their books and feast! Commit your favorite poems to memory and let them work their magic on you.
Don’t lard your poem with trope
Trope is an umbrella term for simile, metaphor, allusion and all that jazz. When I served as a moderator at a web forum, I encountered newbie poems that were almost all trope. Inevitably such poems sound pretentious, they are hard to follow (because they lack a footing in the real world), and they leave a reader confused and unmoved. One gets the impression that the poet is actually hiding behind trope, using it as a defense mechanism, almost.
On the other hand, used judiciously, and with freshness, trope is a fine tool for the poet. I wouldn’t want to live without an image like this one, from Anne Sexton:
I have gone out, a possessed witch,
haunting the black air, braver at night;
dreaming evil, I have done my hitch
over the plain houses, light by light:
lonely thing, twelve-fingered, out of mind.
A woman like that is not a woman, quite.
I have been her kind.
Read Anne Sexton for many examples of good trope and terrible trope, a latter example being “…my heart is a kitten of butter.” Say whut?
Remember that a poem is only as good as its ideas
That the heart is “a kitten of butter” is a silly idea. The heart purrs and mews and scratches while melting on the table perhaps? The heart is an adorable, pettable, vulnerable thing to spread on your bagel? No matter how technically dazzling, if a poem’s ideas are silly or trite or prosletyzing or mean-spirited, the poem sucks. Conversely ….
Remember that a poem is only as good as its technique
No matter how rich its ideas, if it is poorly crafted, the poem clunks.
Keep in mind what a poem is, what a poem is not
Consider the profound, life-giving differences between poetry and other types of writing! The essayist must argue points and organize material in a straightforward, logical way. Not so the poet, who “tells the truth but tells it slant.” The songwriter may rely on melody and instrumentation to put forth a song’s emotion; as a consequence, even the most successful “get away” with cliché after cliché. The poet has words and words only. The novelist, the playwright, the screenwriter, create a sort of macro-reality. Except in epic poetry, the poet creates a micro-reality. Just one poem, well realized, can provide as much wisdom, horror, elation (fill in the blank) as one of those sweeping opuses. Or of an opera, which is the true plural of opus anyway!
Enter the Cloud of Unknowing
Lastly, when you sit down to write a poem, enter a cloud of unknowing. You are not a carpenter, nailing things down tightly, nor a preacher spouting his doctrine, nor a reformer full of cocksure pronouncements and complaint. Be at one with human nature. We are full of contradictions, we humans, we are capable of a whole spectrum of emotions and behaviors, from the most lofty to the most despicable. Rest with the contradictions, embrace the whole spectrum. Recognize our plight as enfleshed, self-aware creatures bound by time and suffering all manner of doubt and pain and longing. Even the most religious of poets (Donne, Herbert, Hopkins) were not overly consoled by their beliefs. “Lord, I believe, help my unbelief” seemed to be their central prayer, as of course it would be, in the realm of the poet, in the fog of the deeply human, in the cloud of unknowing.