Near as I can tell, the first commandment of all great endeavors is, "Thou Shalt Crash And Burn." Generally, the first time. Generally, more than once. Not always, but sometimes. Some times, you will do something, and it will be god awful, absolutely horrible, never in a million years will you admit you tried that, and you will crash and burn. Other times, you'll do something that seemed like a good idea at the time, that seemed at least 3/4 baked, that actually seemed like it might be the thing that works, and you still crash and burn. It's basically inevitable that at some point you will be a smoldering pile of wreckage on the ground.
And you know what, that's okay. In fact, it's good. You want to be the smoldering pile of wreckage on the ground. You'll probably feel awful about it while it's happening, but that complete disaster of a failure is actually good for you. It's how you learn.
My first novel, I thought was quite good. I actually set about querying that thing (Mistake number 1. As any agent will tell you, first novels -- at least, one's like mine -- belong in the back of a drawer in a nightstand in the darkest corner of your attic). Anyway, I had some high hopes for that thing. 25 rejections or non-responses later, I had already learned a lot about writing and publishing, and I knew that thing was basically unsalvagable, and I let it go.
But, with the memory bank slightly more full and an ego slightly sturdier after a few right hooks, I know I've learned a lot from crashing and burning on that first go.
~Subplots are our friends -- generally, the way to keep things going in the story, to keep the tension and interest up, you need to have more than one thing happening at once. Don't be afraid to have other plots going on at the same times as Big Plot. Your readers are smart. They can keep up.
~Adverbs, however, are not your friends -- Yep, I made that mistake. I splashed those things everywhere. And I'm not even sure why. I guess this mistake could just be called Using Five Words When One Will Do.
~Know your characters -- Every now and then, my characters would say things or do things that just weren't in character at all. One of my guy characters sounded a lot like a girl, actually. You've got to know them so that you know what they'd do or say and how and why.
And I learned other things, too. That book, for instance, is what led me to reading blogs, which led to following blogs, which led to writing a blog, which led to you reading this post. Now aren't you glad I crashed and burned with that first book?
My point is, everyone is going to fail at some point or another. Most people are going to fail spectacularly. Some might even get rocks thrown at them in the streets for how badly they fail. But it's about how you recover from those failures that matters. Because if you give up after that first book is a wreck, then you could miss the chance to write something totally awesome that you, an agent, a publisher, a book seller, and everyone and his second cousin is going to love. (Hey, J.K. Rowling wrote a book called Rabbit when she was 6. What if she'd given up before Harry Potter. Just the thought makes me sad.)
So, go forth, everyone. Crash and burn. Fail with gusto and glory. Just make sure you take something away from the experience, too.