So I've written some poems before, and I just wanted to share some tips I've found for writing them.
1. Figure out your subject matter first. Personally, I write from emotion, so whatever I feel at the time or whatever is going on in my life, is the topic. Sometimes I start with an idea and it drifts in a different direction, and that's fine, however, I usually go back and change it a little to be consistent with whatever theme is the most prominent.
2. Title goes last. Titles will usually be whatever the poem is about, maybe a reoccurring line, maybe a word or two. Better to pick one once the poem has been formed, since your subject matter may change.
3. Figure out what kind of format you want it to be. Personally, I prefer couplets, which is pretty much rhyming. I use a website called rhymezone when I need help rhyming words, however, it has many uses. There are many different types of poetry to try tho!
4. Develop a rhythm. Once you start writing, try to make sure it flows well. Kinda like a song. I can compare the flow of my poems to something similar to Little Girl by Faith Marie. When you hear the song, you can hear the rhythm she is making, try incorporating that into your poem.
5. Keep the poem relatively the same length. When you have lines going back and forth between short and long, it can look... unprofessional in a way, and amateurish. Keeping lines similar in length can help the form. If you have an onomatopoeia for added effect to something, then it would be appropriate to have a shorter line. Poem lines should seldom be over a complete line. Meaning, when you are writing, the poem line should not be so long it requires two lines. Occasionally, this is unavoidable, but try to avoid it by using commas or separating a compound/complex sentence. If you are rhyming and have to separate the sentence, try rearranging words and switching between active and passive voice.
I recommend ryhmezone.com for word help (rhymes, near rhymes, common uses in songs, definitions, synonyms, antonyms, and more). I also recommend PowerPoetry for help with poetry types and also just sharing your poems somewhere. Accounts are free and you can get scholarships from PowerPoetry, and some help from teachers a mentors as well.
