Broadly speaking, there are two ways to format a poem.
In my own work, I would normally default to free verse, but in a recent piece, I started writing a triolet before realising that a villanelle has a similar repetitive structure, but allowed more than twice as many lines. The intent was to present as a heated argument between two people, so the repetition worked quite well.
In free verse, by contrast, the form is dictated by the poet in terms of line length, syllable count, where any rhyme is placed, &c. In my experience, this is often misunderstood by non-poets – and even some poets – as it can look like the words are simply chopped-up prose or placed at random, rather than placed there with intent.
It’s difficult to sum up in a few paragraphs how to write free verse poetry, but the best advice I can give is to chop out what you don’t absolutely need. Even when writing to form, I sometimes find it necessary to remove the unnecessary and replace the missing syllables with another thought or a stronger image.
This advice particularly comes into its own with rhyming couplets. If it works for the piece, then that’s great, but consider whether removing the couplets element might make it stronger. I have a lot of experience of hearing second lines that seem to be placed there only to rhyme with the previous line.