I write a lot of shorts and occasionally submit them to magazines, anthologies, etc..., though many also go straight to indie, because they're part of an established series or world or because I have a couple of stories with a similar theme, so I bundle them in a collection. Poems still go to on submission, because there is no real indie market for them. My hit rate isn't too great, but then my work doesn't fit all that well into the current SFF short fiction market, which is part of the reason I went indie in the first place. And other genres barely have a short fiction market at all.
Otherwise, the same rules as always apply. Read the submission guidelines and follow them and read the magazine itself, whenever possible, which is easier now that many/most are online. If can get to know the editors personally, either online or at conventions, it probably also helps. Though if you only interact with them hoping to sell a story, they'll notice.