Without wishing to be prescriptive, there are certain generally accepted dos and don'ts when writing contemporary poetry:
*Try to avoid using archaic language like "thee" and "thou" etc. In fact, avoid any word you would not use in ordinary speech.
* Avoid using elisions such as "o'er" or "ne'er". Elision was a technique used by poets in previous centuries to reduce the number of syllables in a metrical line and looks very dated today.
*Avoid using cliches or worn-out constructions such as "shifting sands" or "dancing daffodils". Look for something fresh instead.
*Avoid using abstractions. "Love", "Beauty", "God", "Truth" etc mean different things to different people. So try to be specific.
*Show, don't tell. Remember Eliot's "objective correlative". Find a way of showing how an emotion affects you or your character. "She is sad" = telling. "She slumps on the sofa eating Mars Bars non-stop" = showing.
*If you use rhyme - consider whether you are controlling it or it is controlling you. If the latter, then maybe you should try free verse or half rhyme.
*Avoid altering the normal word order of a sentence to accommodate a rhyme scheme, as in: "He to the bathroom went."
*Check your poem carefully for spelling mistakes and incorrect punctuation.
*Avoid excessive use of adjectives.
*Cut out every word you dare.
*When you've finished, read your poem out loud to identify any awkward sections.
If you've covered all these points - get posting!