The first key to writing better poetry; is of course to read good poetry. Start by reading all kinds of varying poetry: love poems, lyrical poems, haiku poems, narrative poems, sonnets, free verse and so on. Read them out loud, if it helps you; listen to the sounds of the words, let the thoughts sink in let them touch your senses. This also trains your brain to pay attention to every little detail and helps you learn to write better poetry.
When writing poetry, it’s not simply enough to see if the words rhyme, or when it’s free verse to just string the words together. What is also important is the sound the words make.
Each line must belong to the poem
Each line of your poem should feel like it belongs to the poem. The best poetry line, will fit smoothly with the rest of the poem; in intention, tone and in rhythm. If it does not, try rewriting it.
Don’t give away the theme of your poem to easily! Try not to mention the theme of your poem by word, or name. Instead, build and write around your theme; using metaphors to get to the core of your idea.
Do not give meaning to your poetry
Do not simply attempt to give meaning to your poetry. Just express your thoughts as clearly as you can, leaving a few things unsaid, and others unexplained. It's best to leave the rest to your readers. This is the main difference between prose and poetry. Prose is expository, while poetry lets the readers truly decide for themselves.
Do not be afraid of writing bad poetry! Everyone has flaws, and no one is a perfect poet. Just do your best and be yourself; let the words simply flow. Taking risks is what leads to great poetry, and of course a lot of other great achievements in the world.
Don't be afraid to use plenty of imagery in your poems. People tend to forget words, but images bury themselves deep into the minds. The image might be funny, dramatic, devastating, inspiring, melancholy, or just about anything. The more vivid and well-formed the image, the better the image sticks.
The Time the Water Fell - Curtis Pierson
The water falls,
and it makes me pause,
on my arm,
sparse droplets roll,
looking to the skies,
all clouds are gone,
back to my arms,
and the droplets grow,
does the water flow,
the water falls,
the water stops.