It is one thing to write that brilliant story or book, it quite a different thing to sell it or get it published. The first thing is to make the writing the best you possibly can with the help of editors and beta readers.
Next is to find a suitable market. These are a few places I use to get ideas for places to sell writing, mostly short stories, but they also include publishers looking for longer work.
Literarium is a register site which allows you to look at a broad range of markets and even narrow it down to the kind of writing you do. They list opening and closing dates for calls for submission to literary magazines, web zines, anthologies and contests.
The author page allows you to create a bio and submission letter template. Personally I don’t bother with this as each market will have its own requirements for both.
Authors Publish Magazine is an email newsletter which connects you to information on their website. You don’t get a choice about what markets they highlight, but since the newsletter comes out frequently, the chances are that you’ll find something you’re interested in. They are mostly about literary magazines, but they have covered book publishers and screenplays. They have free resources available through the website.
Submittable is a web site which allows contests, anthologies and magazines to manage submissions. Even some book publishers use the site. Since so many people use the site to list open submissions, Submittable lets you register for their newsletter, Submishmash, which tells you what is open and what is hot. They also have free resources.
Writers Digest is the great granddaddy of market sources. They published a thick tome of possible markets yearly, before the internet was a thing, and had a monthly magazine one could subscribe to. The e version of the magazine is dirt cheap and has great articles along with some suggestions for markets. I stopped using the site because a lot of the advertising in the magazine and the website was predatory publishers. For a writing site, I got very annoyed that they exposed their clientele to companies which they should know were less than desirable.
Another way of discovering markets is to search your genre, say horror stories, and whether you’re looking for magazine or anthology, and submissions. You’ll come up with a list of possibilities. You might want to put the current year in as well to weed out markets no longer looking for work.
A few last comments on submitting your work.
Some literary magazines charge to accept submissions. I don’t like the idea, but I can see how they need to pay the bills. If you don’t mind, go for it, just be wary of anything too large, especially if they are wishy washy on what they pay.
There are also ‘pay to publish’ anthologies. You submit a story, they love it, but you have to pay an exorbitant amount for a copy of the book. I’m of the opinion that authors should get a copy of the anthology they are included in at the very minimum. There are also publishers who vet the manuscripts, but ask people accepted to the publication to pay a fee. These are mostly groups putting together anthologies to show their work, so one could consider it a marketing cost. Even if you get a portion of the royalties, don’t expect to get back your investment in a hurry, anthologies rarely are best sellers.
Just as there are pay to publish magazines and anthologies there are pay to publish book publishers. If they ask you to put up money to be published, you should probably run the other way. There are a few legitimate co-op publishers who share costs and revenue with the author, but do your research. The Alliance of Independent Authors website has a ‘watchlist’ of the worst offenders.
One strange place to look for places to submit work is Kickstarter. I’ve had a couple of stories published through books funded on the crowdfunding site. Some anthologists will begin their campaign with the slate already full, while others look to fund the book and then open submissions. It makes sense if you don’t want to invest a lot of money in something which doesn’t gain traction.
A last note on submissions. Always go the the publisher’s website and read their submission guidelines carefully. Copy them and refer to them when formatting and preparing your work. Every publisher will do things a little bit differently, and you don’t want to be rejected because you used the wrong font, or put your name in where they didn’t want it.
I know one publisher who deliberately uses a particular font, font size, spacing and margins unique to them for the sole purpose of weeding people out who can’t follow instructions. They say as much on the bottom of the page.