Curiosity is the mother of creativity.
Here is an exercise. Take a poet or two and define their attitudes in as much detail and nuance as possible, with the fullest exercise of your own curiosity. If you aren't getting any attitude, then find a poet you know better, or one for whom you have a stronger reaction. Don't pick one to whom you are indifferent.
Say your first impression is that the attitude is one of "exuberant nonchalance." That would be a good place to start. Then you would try to figure out what is really going on there. Is the nonchalance a pose, a defense? How does it vary from poem to poem? You don't have to worry about getting it wrong, because it is what you feel in relation to the text. I used to have this argument with people about Frank O'Hara's poetry. They thought his emotional range was limited, whereas I saw it as very broad. Of course, I was right, but they were not wrong. They just hadn't responded (yet) to as many things in the poetry as I had. For example, the phrase "In Memory of My Feelings," the title of a poem by F O'H, reveals a complex attitude, or "Meditations in an Emergency." Or titling a poem after a skin-care product, like "Biotherm." That is fucking hilarious, because who else would have done that?
Berryman thought Stevens was emotionally cold, and that Creeley was boring. So what he was really saying was that their attitudes were not something that he could respond to. He was correct, speaking for himself. A strong dislike of a poet's attitude is something to be respected, after all, because the reader has an attitude as well.
Or try it with Emily Dickinson. You might start off with a cliché version, which is fine. So you'd think of a reclusive person with a slight coyness, and also a sharp wit. But that cliché already has some nuance to it. Then add to that her ecstatic mysticism! Then ask how that lines up with the wit and the reticence, the idea that she's not going to treat you, as the reader, like a stupid person that has to be told everything explicitly. She is very modest in the worldly sense, but she also knows very well her own worth and intelligence. Her emotional range goes from ecstatic joy to abject depression. The verse form seems simple at first, since it is all ballad / hymn stanzas, but that is just an illusion, since every line has to be performed rubato. In practice it's almost free verse.
Even just unpacking or questioning the cliché a bit gets you very far. You go from a single adjective or phrase to a sentence, from that to a paragraph's worth of insight or more.
With William Blake, I would start with the ideas of innocence and experience. Is innocence a mask? Can the savvy poet really talk with an innocent voice? What is really going on? Is experience really all that different from innocence in its core emotional tone? How does paradox function? How sure of himself is he? When he says "The dog starved at his master's gate / predicts the ruin of the state," there is a kind of shattering of delusions. Everything is connected, and it bursts into the poet's consciousness with abrupt force.
If you don't read with this attitude of curious attention, you won't get any of this.