The Craft of Writing Science Fiction That Sells

Ben Bova, best-selling author and six-time Hugo Award winner for Best Editor
explains step by step all the elements you need to write profesionally
selling science fiction. Bova was editor of both Analog and Omni magazine,
two of the best-ever markets for short fiction, as well as a best-selling
novelist -- so nobody knows what sells better than Ben Bova. The book
breaks down every aspect of writing and analyzes it in depth, including
with complete example short stories that he examines for how they tick.
The book targets science fiction in particular since it's one of the
hardest genres to write, but his explanations are applicable to fiction
of any genre.

This is a must-read for anyone trying to break into the professional
science fiction writing field.