What to write about
Poets tend to write about things that they feel strongly about.
Your first job in poetry is to find out what affects you the most. What things have the most emotional effect on you? This may change from day to day, but most poets find they tend to have a theme within their style – mine for example is nature. You will rarely find a poem I’ve written without some mention of nature or use of natural imagery.
The topics you choose might seem trivial, but if they cause a powerful reaction in you, then you will be able to write honestly and strongly about them, and make them seem no longer trivial to your readers.
However, keep in mind that its importance to you personally must be successfully conveyed to the reader.
Don’t make the mistake of believing that strong subject matter equates to strong poetry, you must still fulfill your role as the poet, and convince your reader that this is an important issue as well. This will be more easily accomplished when you feel strongly about the theme yourself.
In other words, once you discover the things that affect you, push it another step. Think carefully about the things that effect you, and figure out why you have that reaction.
You may find that you then have the subject matter for a poem (or, more likely, many poems).