After 20 years writing haiku and getting them published, I feel qualified to share my knowledge. Feel free to disagree or add anything else you feel I've forgotten in the comments.
- Keep haiku concrete (present images, scents, sounds, etc), to let readers feel the feelings for themselves, rather than telling them how you feel.
- At least at first, try to keep to three lines, short-long-short, with the syllable count up to 17 syllables but preferably shorter, (though some accomplished poets write one, two, or four line haiku.) It is said that 13 (3-5-3) English syllables approximates the 17 (5-7-5) sound units of traditional Japanese haiku.
- Write haiku in two sections: one shorter on one line, and the other running over two lines. Either section can begin or end the haiku. If these two parts create juxtaposition, it will produce dynamism.
- Keep it succinct. Only use words that are necessary, but don't make it sound like a telegram.
- Use active verbs. 'The cat sniffs' will always be more dynamic than, 'the cat is sniffing'
- Only use necessary descriptors. e.g. one doesn't usually need to know snow is white or cold, but one might need to know if it's slushy, or grey or pristine.
- Write lots.
- Read more, especially from edited journals. (links below) Some journals will have an editorial bias, but a more of what one reads from those sources is likely to be good than in personal blogs or other unedited places. Of course, there are many great poems on personal blogs and some consistently good poets who hardly ever submit to journals.
- Educate yourself by reading the essays in journals. Learn from the best.
- Keep your senses open. Keep notes to help you remember sense-based details.
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my haiku contemplation
the voice of a crow
The British haiku society also has great info and good up-to-date links
Michael Dylan Welch has lots of essays and other interesting stuff on his site: Graceguts
A link to lots of haiku and related journals on Ray Rasmussen's site Ray's Web.
I learnt a huge amount from Aha Poetry. Very practical exercises and information.
I could go on, but I trust most of these links to give sound information and good poems. I would add that, if in doubt while browsing haiku sites, go to their 'What Haiku Is' or 'How to Write Haihu' instructions and, if the first instruction is to write in 5/7/5 syllables, it is very likely that their information is based on misinformation. If they add the magical words 'up to' (as in 'up to' 17 syllables) they are likely to be closer to the mark. The trouble with this paradigm isn't the misinformation about syllables (lots of good haiku have been written in 5/7/5 English syllables) but that they often miss the very things that make haiku deep, rich and engaging.
Good luck and may your path be paved with pine needles or autumn colour or blown petals or everyday gravel with poems in it.