Write concretely as opposed to abstractly. Although abstractions, like love and hope, are often the impetus to write poetry, they are also universal and generic and it is better for you to write about these abstractions in a unique and specific way. Concrete language describes things that can be accessed with the senses -- things you can feel, smell, see, taste and hear -- and since your sensory experience of world is different than anyone else's, if you write about the concrete objects that compose your world your writing will certainly be unique.
Use devices such as assonance (the repetition of vowel sounds) and alliteration (the repetition of consonant sounds) to give your words the quality of a song, which similarly depends on repetition of sounds.
Use metaphors, or you can even organize your entire poem around one metaphor. Transformation through metaphor is often at the core of poetry, changing flowers and fishes into objects of great beauty and symbolic importance.
Find strong verbs. Strong verbs can perform the same function as metaphors without having to make a direct comparison. You don't have say, "I ran like a mouse in the dark" when you could say, "I scuttled in the dark." Scuttle is inherently associated with rodent-like movements, so the reader can make that comparison without you doing it for her.
Use your own lexicon. Whether you are a mechanic or a florist or a yoga fanatic, don't be afraid to make use of vocabulary that you might worry isn't accessible enough for other readers. An unusual word is just another way to make your poetry stand out, and most readers are willing to learn something new.
Borrow from the poems that you love. Imitation is the most common mode of learning -- it's how you learn to speak. Those poems that you love often inspire you, so see where that inspiration takes you. Borrow interesting words, even whole phrases and lines to initiate your own creation. Just acknowledge your source.