One of the most important—and difficult—factors in becoming a better writer is the willingness to accept criticism of your work. Now I am not for a moment talking about superficial criticism (“I liked it”/“I didn’t like it”) or pejorative criticism (“it sucks”), but about substantive criticism of form and content, which can identify why something in a poem is more or less effective. It is important because without this kind of feedback, a writer is likely to continue to make the same mistakes and encounter the same difficulties. It is difficult because first, you have to know a critic who knows what they are talking about, and second, you have to be not be so danged sensitive.
That second issue is more than simply common among aspiring poets; I rather think it represents the normal attitude. For our contemporary culture regards artistic creation as a highly personal experience (indeed, we have quite spiritualized it), identifying it so much with the person that any criticism of their art is perceived to be a criticism of their person. But once upon a time, poets knew better; and could have their work criticized as any craftsman, composer, or architect could have their work criticized. We need that clarity of mind now: the object of criticism is the work, not the author; and it focuses on the developing the skills of that author, not their personality.
A poet’s work may indeed be a work of self-expression; but when we are thinking clearly, we remember that when one expresses themselves, they are hoping to be understood by another. So the first task of criticism is to clarify meaning: what did the reader understand the author to mean? Is the understanding of the critic acceptable to the author? And if not, what might the author do to clarify his or her meaning?
The emotional hurdle to overcome at this point is the author’s assumption that the critic simply missed the point (which is possible; but I hope you are consulting perceptive critics here). “Oh, you just don’t get it,” the author may huff. Why? Is the critic imbecile? Biased? Lacking important information or experience? Or perhaps, just maybe, the author left something out, or was overly cryptic. Consider the possibilities.
After the meaning has been worked out, the critic may also point out some structural issues or word choices that affect the rhythm, flow, impact, or atmosphere of the poem. Some of the criticisms at this point will be based upon rules (or guidelines) of established poetry; other will be matters of taste. Each prompts a different set of emotional obstacles.
Regarding questions of rule (for example, on metrical anomalies), an author may feel insulted (for nobody likes being told that they are less skillful than they think); and a common retreat is to simply reject the rules, or claim that this is a justifiable exception to them. Now, indeed sometimes an exception is more effective than the normal rule; but usually not. I advise newer authors to be humble about this, and consider: the rules (or established patterns of use) are not arbitrary, but reflect a purpose.
(Note: if you are writing free verse, beware—it appears lawless, but there is method to such madness, and the best free verse poets have hidden “rules” or their own. Now if free verse better suits your purpose than metrical verse, good luck with that; but don’t fly to free verse simply to escape the rules or meter. That’s a recipe for bad writing there.)
Regarding questions of taste, the author must be willing to entertain opinions, even if he or she will, after consideration, disregard them. For in such matters, one critic may deplore what another applauds; and no poem will suit all audiences. But take note if all your critics express similar thoughts on such matters: for if your work suits only your taste and none others, you may want to consider a different tact. After all, if you want to communicate (and I am assuming that all words are for communicating with others, and not narcissistic self-gratification), you cannot expect to do so on only your own terms.
Naturally, it will be impossible to satisfy every critic—but it is very possible to satisfy some. Which critics an author seeks to satisfy will affect what audiences that author can effectively reach. I don’t expect every author to speak to the same audiences; but I encourage them all to learn to at least speak to more than an audience of themselves alone.