I once read where a very prominent writer commented that a professional writer is just an amateur who didn't quit. Persistence is the first P in writing. Even though I was accepted for an assignment on my first pitch to an editor, that usually doesn't happen. Many, many writers have to pitch, or query, several times before they receive their first "real" writing job. Rejection is something every writer will experience. I've certainly had my fair share. Don't quit when you get discouraged. Keep at it.
Patience is the second P. Until you are established, even acceptance calls/emails will be slow to come your way. Don't panic, or give up. If the story is good, people will like it. This includes editors and publishers. It took me months, with repeated phone calls to an associate editor, to land a feature article with a prominent journal. Once that first piece ran, the same editor invited me to write for them again. Turns out, that first feature had been informative and entertaining and had garnered some very positive feedback. It'll take a while, but good writers will get noticed.
The third P is perseverance. Again, keep at it. Just because I've had several articles published, along with two books by indie publishers, doesn't put me at the top of any literary agent's list of must-have authors. I'm in the process of sending out query letters for an historical fiction novel. It's a unique story about a place that no longer exists. I think it's great. I think it should be published. I think it will be a hit once it is. But, convincing others can be a daunting task. With millions of writers, the market is saturated. A great query letter needs to stand out from the crowd. This takes editing, and time. Failure is great teacher. Look at it that way. I've learned to do just that. While editing the book I thought was awesome just the way it was (5th draft), I discovered that it needed more work. Cutting is just as hard as adding. In sports, we used to say "tighten up". That's what needs to be done to any manuscript. When you think it's done, put it down for a while and then go back and work on it some more. When it's polished until it really shines, you'll be able to do that to your query. Guess what? You'll be on the doorstep to success. This same advice applies to self publishers as well. W-O-R-K. Keep at it.