Start with the highest paying magazines and work your way down. The highest paying magazines also tend to be the most reputable, though not always. There's nothing wrong with getting work published in small magazines, but they usually pay less and don't have as many readers as the bigger magazines.
There are many other ways, such as self-publishing, putting your work online, or reading at open mic and spoken word events. None of these activities are any better or any worse than the others. They each have their own advantages and disadvantages. It depends entirely what is important to you with regards to your poetry. What do you want? Would you prefer to be well-known, or widely-read, or make money, or entertain people, etc, etc...?
the more well-known and respected the venue, the more well-known and respected you can become, as a poet... or a short story writer, or whatever...
I think that this is one of the best ways! Having your work in legitimate magazines is a great way to boost up your portfolio and get your name out there. Look around for the best/most well-respected publications and aim for those. If you have any particular poets whose work you love, find out if they're editors anywhere and submit there. It's all about building a network and getting your name noticed. Go for it
I think it's the only way to get your name out there. I mean, there are other ways, but there's not many other places that sell poetry, and publishers aren't going to be taking on any new poetry books, unless you're a celebrity, or Charles Simic.
Indeed, publishing poetry or any respected work of literature is important. For thoughts and experiences are being shared; They are one of the most important thing in life; they help us apply what we intend to do. Of course, we should seek the well respected magazines, who are administrated by well respected people like this respected website and its members.
The size of a venue doesn't matter as much as its reputation. Let me speak about short stories for a second. Many people want to publish in say, The New Yorker. So there are short story writers who will send everything there first and then work their way down until someone publishes them. The problem is, if you write horror stories about men who throw puppies into wood chippers, it isn't going to get published by The New Yorker (barring some major shift in their target demographic.) But, there are horror lit magazines and publishers who have devoted followers. There are horror venues that, within the horror community, command quite a bit of respect and have reputations for publishing amazing horror. If you publish in a little known poetry magazine, you are only really setting yourself up to be a little known poet. But if you find magazines that readers of poetry read and respect, you are positioning your work in front of the largest available concentration of your target audience. That's a good thing. I will say that occasionally I will write a story specifically for a small, lesser known venue. I don't so it for exposure. I do it because I believe they have solid editors and a good idea and, in time, they too could be a respectable publisher of short stories.