Many people struggle with writing poetry because they are intimidated by all the rules and fancy language often used in poems, but one thing to remember is that poetry is an expression of one's thoughts, which means rules do not always need to apply. If a writer wants to begin writing poetry in a certain style — writing quatrains or sonnets, for example — the best thing he or she can do is study the style of such poems. If a person simply wants to express thoughts in poem form, however, the best place to start is with a pen and paper.
A poem can focus on just about any topic, and while some types of poetry focus on specific topics, much of poetry can be written on any topic the poet chooses. He or she should therefore decide what idea needs to be captured when writing poetry and begin formulating ideas for capturing that idea. Some poems rhyme, though many do not, so if the poet is interested in writing poetry about a specific topic, a rhyme scheme may only get in the way. Try writing about the topic without a rhyme, then perhaps play with different rhyme schemes in a subsequent draft of the poem.
One of the pitfalls of writing poetry, for many writers at least, is the cliché. Clichés are words or phrases that are overused to the point of becoming almost meaningless. Phrases like, "It was a dark and stormy night" have been used so often that they often elicit eye rolls from readers. Try to avoid clichés; they are often associated with melodrama and a lack of creativity; many writing teachers will tell students that if a phrase comes to the writer exceptionally easily, it is probably a cliché.
Perhaps the most important tip for writing poetry is to read a lot of poetry. Reading poetry will help the potential poet understand the conventions and trends in poetry, and it will help the new poet learn clichés so he or she can avoid them. Reading poetry will also help the new poet develop a style of his or her own, since the poet is likely to identify other poets he or she enjoys reading. A poet often starts by mimicking the style of an established poet and then modifying that style according to his or her own writing talents; this is a good way to start, and one's talents will continue to develop over time.