Find short-story, flash fiction or even novel competitions and commit to entering them. They provide invaluable deadlines and offer the additional advantage of keeping the manuscript you have submitted off your desk for weeks or even months.
By the time you learn that you didn’t win the competition, you will be ready to revisit your submission with a fresh eye. Your edits will improve it, and you will have a piece of fiction ready for submission elsewhere.
And if you do win… well, that is always a nice thing, too.
Note: Many writing competitions now include entry fees. If these fees seem to be appropriate — a reasonable sum to cover administration costs and an honorarium for judges–don’t let them discourage you from entering. More and more literary journals are using such contests to help defray operating costs, which makes good sense. In most cases the fee will cover a copy of the journal or a one-year subscription in addition to the opportunity to enter. The key word here is “appropriate.” Some competitions charge excessively and their only purpose is to make money for the organizers. Caveat emptor.