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.
This is an excellent point. If you've finished a work. It needs to be sent out to publishers or agents until you succeed in selling it. Sending it to one or two is a waste of your writing. It is unlikely that the first or second or even the fifth submission will be accepted. It is a constant part of becoming a published writer.