Asimov's Science Fiction is considered by many to be the foremost science fiction magazine in the world. Since its inception, stories from ASIMOV'S have won 38 Hugo Awards and countless others. Each year ASIMOV'S brings Cutting Edge science fiction and fantasy stories by the best writers in the business as well as rising new stars, including writers such as Ursula K. Le Guin, Robert Silverberg,Connie Willis, Greg Egan, Nancy Kress, Michael Swanwick, Mike Resnick, George R.R. Martin, Stephen Baxter, and many others.
The Science Fiction and Fantasy Writers of America, Inc. offers writers many valuable services. They produce a newletter with market info, they have a number of committees including one for grievances, they will supply model contracts and advice to new authors and and so on. If you plan to write science fiction and fantasy and can meet their membership requirements, this is for you.