I would recommend Poet's Companion it's got sections on technique as well as prompts and exercises. Used it in college.
I'd definitely recommend the poet read more, well, poetry, however like, not just random stuff online, but actually published contemporary work. Seeing that this is all taken from their diary from ages 12-19 and self published it seems like a fun little personal project. If I'd grown up with self publishing being so user friendly I might have done something similar, because before you actually get serious about poetry, the popular concept of poetry is very different. It's thought to be all feelings and big ideas and deep thoughts... but in reality, contemporary poetry is stuff, it's anchored in tangibility, it's often multilayered with literal meaning, figurative meaning, connotative meaning, references/allusions etc. But you will often find your passion for poetry before you have studied the craft at all, and you don't know to even seek it out.
I definitely recommend Poetry 180 as a good starting point for more serious poetry reading because it's still really understandable/accessible but it has that extra layer of craft you often won't get in random internet poetry reading or Insta-poetry.
That, and/or either <em>The Poet's Companion</em> from Dorianne Laux and Kim Addonizio, or <em>In the Palm of Your Hand</em> from Steve Kowit. Both are great introductions to craft with contemporary examples from accessible poet-editors. And both give tips and prompts to help the poet work the new craft tools into their writing right after learning about it, which I highly recommend doing. Great books for anyone that doesn't have them.
I mean, sure, but haiku are so short they are often more confusing to new writers. They require a lot of inference. I think just doing close reads with a guide, like a textbook/essays, but much more preferably, with a teacher who can actually answer questions, is the best way to go about it. Classes really are awesome, though of course, YMMV. All teachers are not equal, and sometimes your favorite writers are terrible at explaining things. I always recommend Dorianne Laux and Kim Addonizio's book The Poet's Companion: A Guide to the Pleasures of Writing Poetry and Steve Kowit's book In the Palm of Your Hand: A Poet's Portable Workshop to young writers. They use good poems as models and help the writers utilize the craft and technique in their own writing.
I'd start with reading Poetry 180. Contemporary and accessible poetry, a really great place to start to see what sort of poetry is being written and published now. If you dig that and want to try it yourself or better understand the craft behind it, I'd highly recommend picking up a used copy of 2 books, together it should be like $15 with shipping and everything. Those books are
1) In the Palm of Your Hand: The Poet's Portable Workshop edited by Steve Kowit
and 2) The Poet's Companion: A Guide to the Pleasures of Writing Poetry edited by Kim Addonizio and Dorianne Laux. The books will teach you poetic techniques, show you how poets have used those techniques, and gives you prompts that have you use those techniques/themes.
Mostly reading gives me inspiration to write. Though sometimes I too struggle with that seed crystal of an initial idea to form the poem around. I've found that working from prompts helps with that. I'm out of town atm so the the last couple days have been no bells and whistles, but check out Notebooking Daily and browse around, try a couple exercises. They are all designed to be written in 30 minutes or less for the initial draft to avoid hanging up or getting 'stuck' anywhere.
That and just reading tons and seeing what it sparks in you, taking note of the techniques of other poets.
These workshop books are also super useful. If you can, definitely buy one of these two books used, they're pretty cheap and used is plenty fine for this use:
The Poet's Companion is edited by Kim Addonizio and Dorianne Laux, both tremendous poets in their own right. This one is more oriented in using poems to spark your own writing, but it does have a good amount of poetry in there, and the craft essays are brief and to the point.
In the Palm of Your Hand: The Poet's Portable Workshop edited by Steve Kowit is also a great textbook for producing your own writing by looking at certain aspects of other poems. Stylistically this is similar to The Poet's Companion, and both are tremendous. Used they're each only $6 with shipping too.