I've collected a lot of rejection letters over the years. Most editors like to keep rejections short and to the point. Now and then, an editor will offer a bit of helpful advice. The best advice I ever received from a rejection letter came pretty early on in my writing career and it was just one sentence: "good writing offers the reader a clear window... "
This advice works just as well for poetry or prose. The basic idea is that you avoid putting anything between you and the reader that makes it more difficult for them to "get" your message. This doesn't mean you can't write ambiguously, or even mysteriously, but it means you should always write with purpose and always be mindful of your readers.
Here are some bad habits that make your "windows" dirty:
If you're writing prose, almost without exception, there are three things the reader must always know: who is on camera, what they are doing, and why they are doing it. Yes, you can blur the lines here for effect or to create suspense, but a little goes a very long way.
With poetry the reader needs a good enough grasp on your images, rhythms, and theme to follow all the way through the poem.
The good news in all of this is that simply being aware that writing acts as a "window" for reader should help.
The even better news is, you can keep coming back to this blog for more tips!