Don't expect to make a living at it. No one has made a living at writing serious poetry since Alexander Pope (born 1688). Robert Frost wrote someof the best poetry in the US in the early part of the 20th century while he made his living struggling with a farm and teaching Latin. Wallace Stevens, another great Modern poet, was an executive with an insurance
company.
The fact is that the audience for serious poetry is so small these days that no one can expect to make even a meager living at it. I rather suspect that that may be a good thing, since poets need as wide as possible experience of being human, and being a professional poet would likely be very confining.
Educate yourself in poetry. The better educated you are, the better poet you can be. I don't mean "educated" just in the narrow sense of stringing a list of letters after your name (B.A., M.A., Ph.D.), though that sort of thing certainly helps. The more you have read in the sort of books that do more than just kill time, the more you have lived with variety and intensity, the better you are likely to be as a poet. A good college course in Creative Writing can help, but spending several years reading the Classics will help even more, I suspect.
I am not an advocate of publishing confessional poetry. Many persons use the flexibility of poetry as a way of getting their more difficult emotions down on paper and dealing with them. This is probably a very good form of psychotherapy, but until those emotions are in some way "objectified"--that is, taken out of the writer's inner world and made accessible to everyone--I don't think it is art. If you write a good deal about the sorrows of your life, it may really help you deal with those sorrows, and as such it's a good thing. But think very carefully before you start making those poems public.
Don't try to manipulate your audience in a crude way. Don't try to convert them to anything or make them do anything. If you're writing poetry in an effort to save the world or make people love you, I may certainly wish you luck, but I doubt you'll be much of a poet. Good poetry, I think, should draw its audience to it, not grab them and force something on them. I keep a print of a Rembrandt painting in my office that I never tire of looking at. It's a picture of an old man with what looks like a towel around his head and a book in his hand. Rembrandt does not seem to be saying anything about saving trees, becoming a follower of Islam or ending world hunger. Still, I think that somehow I'm a better person for having seen that picture. In ways that are very subtle and complicated, the painter draws me to his image and I am changed by the process. Maybe poetry will save the world, but if it does, I think it will be the way that picture has changed me.
Finding "your voice" is probably the most difficult and essential part of writing poetry. Most young poets (of any age) start out writing imitations of poetry they admire. There's nothing wrong with this, and indeed it is probably the best way to learn. I recommend you take as your early model some poet who is usually thought of as less than a world master. Trying to write like Emily Dickison is simply impossible, unless you are being satirical, but it is possible to imitate, say, Longfellow with some success. But no matter how well you write like Shelley or Arlington Robinson, if you have any real talent you will one day realize you are yourself, and you need to write in a way that no one else has written. Then you will begin to really find your voice.
Revision is, I think essential. Horace, who wrote great poetry about 2000 years ago, advised, “when you write something, put it away like fresh wine and let it age nine years before you publish it.” Nine years may be a bit much, but I think the advice is good. By putting a poem away for a while, you can come back to it having somewhat forgotten the emotional and intellectual circumstances that triggered the poem. The poem becomes, not a joy or a heartache, but what poetry really is--words on paper that constitute a work of art (the Mona Lisa is just so much paint on a piece of wood, though the paint is arranged with exquisite talent). With that kind of dispassionate look at the work you can revise or discard it with more real insight.
You must be patient and persistent at writing poetry if you are to make progress. I like to tell the story of a great Japanese painter in the middle ages. He was a master of the "free-brush" style--painting very quickly on rice paper with a brush without the possibility of revision. The Emperor commissioned a painting of bamboo from the famous painter and sent him a great deal of money for it. Months passed, then years: no painting came to the Emperor. Finally the Emperor sent a courtier to the painter to make a polite inquiry. The courtier and the painter had tea and chatted for a while; finally the courtier asked: "Oh, by the way, what ever became of that painting of bamboo the Emperor commissioned?"
"I've been meaning to get around to that," the painter said, and took out his paint and brush and rice paper. In a few minutes as the courtier watched, he produced an exquisite painting, perfect in form and line, one that seemed to catch the very essence of bamboo.
"This is for the Emperor," the painter said, bowing.
"It is perfect!" the courtier exclaimed. "I shall take it to him with great pleasure. You have made a masterpiece worthy of all the money he sent you, yet it took only a few minutes."
"Kindly open that closet before you leave," the painter said.
The Courtier opened the closet. A stack, taller than he, of thousands upon thousands of practice sketches of bamboo fell out.
I think poetry should be essentially an oral art. Homer, Sophocles, Shakespeare, the greatest figures in the Western poetic tradition, all wrote to be heard, rather than to be read. I dislike the sort of poem that is so complicated it must be taken apart like an algebraic theorem to be understood. On the other hand, I like the sort of poem that can be read aloud by one person and enjoyed on the first hearing by another.
I strongly recommend that anyone seriously interested in poetry learn to read it aloud. That is a difficult art. You must learn to pronounce words clearly, with the proper inflection, rhythm and emphasis, and do it without calling attention to the fact that you are doing it. "Pause at the end of the line" is a rule that was taught to me, "no matter what the grammatical sense." Try reading aloud to a friend. Get a book of good, essentially oral poetry (Robert Fagel's translation of the Iliad comes to mind), and read aloud. Observe what works, the way that an oral poet must repeat and re-emphasize certain things so that the audience remembers them (in writing intended only to be read such repeats are an error, since the reader can turn back a page and check on matters). The point is that the poet is thinking not of him- or herself, but of the audience.
Publishing poetry is a difficult matter. As I've mentioned, there isn't much of an audience, so the number of journals and magazines that carry serious poetry is small. Book publishers that publish poetry are even fewer. Avoid publishers that will publish your poetry for money--not only is that expensive, but very few readers will respect poetry that is published by a "Vanity Press."
When you finally get something good enough to publish (likely this will take years to do) it will be a struggle to get it published. I recommend that you look about in a large library (university libraries are best for this) till you find some publisher who prints poetry that really resembles your own. Look that publisher up in Writers Market (the library should have a copy) and start sending off manuscripts. Expect to be rejected the first time, and many times after that--it's part of the game.