You've just spent the last year or so reading everything you can on writing. You've attended a workshop or two. You've burned the midnight oil stealing spare hours of time to knock out a half dozen stories.
Now you think you're ready to start submitting.
You don't THINK you are. You KNOW you are. Even if you only THINK you are, it's something you just need to DO.
But how, exactly, does one go about it?
Most writers at some point become familiar with The Writer's Market. It is the whole-industry standard that offers several options for access. One option is to go to the bookstore and buy a copy. It's huge--3 or 4 inches thick--and packed with not only listings of writing markets but listings of editors and agents, as well as articles on the business and craft of writing. A 2010 copy should be useful for a couple of years. Beyond that, because markets come and go so fast and editorial boards change so much, the information will be outdated.
A second option with The Writer's Market is to check out a copy at the library. Most libraries stock the current copy of The Writer's Market. It may be a non-circulating reference volume, but you can stand to spend an hour or so looking through it and taking notes.
Your third option with The Writer's Market is to subscribe online, for which they offer several options. You can purchase yearly subscriptions, monthly subscriptions, or 'niche' subscriptions that allow you access to market information specific to Children's Poetry or Short Story & Novel markets. I know of many writers who buy a one-month, full access subscription, spend that month searching markets, then cancel their subscription once they have the information they want. Later (six months to a year) they may do the same thing to update their database.
I really think The Writer's Market is the only market search tool I can safely recommend for purchase. With this one exception, keep in mind that money should flow TOWARD the author. You should avoid paying to be published, or to procur an agent or editor. The only reason TO pay to be published is if you're interested in printing a few dozen copies of your book to give as gifts to your friends and family--a 'for the love' publication. Too many of the what are termed 'vanity' publishers are in it to take your money without helping you make a name for yourself as a viable author.
Outside of that, there are many free online market searches available, usually specific to genre.
The best general market search site is Duotrope's Digest. Duotrope's uses numerous fields in which to narrow your search and allows you to order your results by a number of different parameters, like pay scale, title, or acceptance rate. Duotrope's also updates market information frequently and takes user-submitted statistics on market behavior--like acceptance rate and speed of response. I use Duotrope's frequently.
Fiction Factor sports a tidy little listing of markets in several genres and categories, including contests.
BellaOnline give a listing of markets and market search sites mainly for non-fiction. Some of those are probably paid market search sites, so proceed with caution.
The Market List has tons of markets listed, but it's not searchable by any other parameters but genre, and leaves it up to you to check whether the market is even still viable.
The WriteMarket.com has a listing that's not huge, but it has a lot of variety, and lists markets specific to certain kinds of writing--like greeting card freelance writing, young writers, business writing, as well as general fiction and nonfiction. I might have to check out that greeting card listing. Might be worth a try to bring in a few extra bucks!
A couple of market searches specific to sci-fi and fantasy are Ralan's Webstravaganza and Storypilot. I frequent both. Ralan's is especially good at keeping their listings updated as to market status, and lists can be sorted by payscale. Storypilot, though less active (as of today they haven't been updated since January 8th, 2010), has a number of search parameters to narrow down your listings for you.