You must keep sending work out; you must never let a manuscript do nothing but eat its head off in a drawer. You send that work out again and again, while you're working on another one. If you have talent, you will receive some measure of success - but only if you persist.
OK I admit the part about "if you have talent" scares me, because then it starts a litany of negative self-talk messages. Maybe I'm not talented, maybe I won't succeed, maybe I'm wasting my time, but then my writing nag voice (who is very positive) takes over. You will succeed, you are talented, persistence, persistence, persistence. Today, as part of your daily writing write a one page letter telling your negative voices why you will be successful. Now get back to work!
The Writing Nag