Maybe because every single thread here is, in the end, about writing better poetry. The Critique subforum is full of the works of people trying to improve their poetry writing. It's a much better place to start than the search function.
I think you'll find that, if we agree on one thing here, it's that there's no silver bullet, no formula. If there were, I know I wouldn't give a dam about reading or writing it; it wouldn't be interesting, diverse or beautiful. There's no shortcut: if one wants to write better poems, one has to read and write poetry and the literature about poetry.
Having said that, I can recommend a couple of readable, helpful, informative and eminently enjoyable books:
- The Poetry Home Repair Manual, by Ted Kooser
- The Ode Less Traveled, by Stephen Fry