Haiku is generally written in two parts, not one run-on sentence. There’s a fragment normally in the first or last line, then the body of the haiku. Consider the first or last line as the setting, then a defining subject or action in two lines.

Haiku is written in the moment; in present tense, with three lines short, long, short. Avoid fleshing out the lines with pronouns, adverbs and adjectives.
         i.e., instead of “the leaf fell slowly” – how about “green leaf floats to earth”

Haiku includes some element of nature. Haiku normally has a season word kigo to set the image. Although it’s not required in western haiku, it is a focal part of the Japanese tradition to have one; and nature appears somewhere in the image visual, aural, sensual.

You don't need to say 'spring' or 'summer' but use a word that evokes the season. For example, think spring with animals - tadpoles, butterflies, frogs, ducks, robins; with plants - azalea, apple blossoms, crocuses; weather - melting snow, warm shower.

Haiku is not egocentric; does not use personification, simile, metaphor, but simply states the essence of the moment, without value judgment or personal interpretation. The reader is given a snapshot of life through the eyes of the poet.

Punctuation is rarely, if ever used, as is capitalization. Keep it simple, straightforward, and sharp.

Haiku often includes juxtaposition, placing two images side by side. For example, the first and second line complete each other; the first and third line complete each other, both making sense on their own and conveying two different images. This often works with the nouns which can have meaning also as verbs.