You can write

As I think back over the last few years, I realize that a lot has changed, and a lot hasn't. I may have a few more books under my belt now, but I'm just as unsure of myself as the day I did my first pitch to an agent. Today, I'd like to talk about our fears as authors.

Self-Doubt
I'm not good enough. Seriously. It doesn't matter what I've written or the epic stories that are currently  whirring around inside my brain, waiting to be typed up... I'm just not good enough. Now, I know, I know, some of my friends that are reading this right now are getting ready to give me that kick in the pants they're so awesome at doing, but I just have to say that it's true. I think this just comes with the territory. I don't know a single author who doesn't fret over what they've written. The key is to just try and believe in yourself.

What If's will kill you
I, for one, am a worry wart. I'm a nutcase - never being able to make decisions and always wondering "what if?". Should I write so-and-so's story now, or someone else's? Should I write my story in first or third person - or both? Should I have long chapters or short? I can't tell you how many times I've written entire chapters in two different ways so that I could figure out what felt right. There really isn't a fix I can give you for those of us who just can't seem to decide what to do. All I can say is: just let your characters roll with it. It's your job to write what they give you. If a certain character is motivating you today, write about him/her. If a different character is pushing you tomorrow, give that one the spotlight. Very rarely will you get anywhere by trying to force a story out of someone who isn't ready to tell it.

Your story will never EVER be perfect
This is true. You will finish your book and go through X number of edits before you might feel like it's ready to submit to a publisher (or self-publish if that's your route). You'll probably have read the words "The End" at least five times, and you might even hate your story by the time you're ready for that next step. I've been there. I've done that. And then I've sent off my query letter, synopsis, and (in some cases), the full  manuscript. As soon as you hit that send button, those doubts fill you and you think, "Crap, did I change this? And did I ever change that his eyes were blue instead of green? Or, did I write enough detail, or did I head hop, or did I..."
You get my point.

My suggestion is to make notes as you think of those problems. If you've already sent off that full manuscript, at least you'll have a chance to make those changes during the editing process. If you've only sent off your query and synopsis, then I'd sleep on it (again, take notes as you think of fixes) and go back in after at least a day to make those changes. You might hate your book by the time it's published, and you might feel like everyone will hate it as much as you do at the moment (we authors can have a love/hate relationship with our book sometimes). Don't worry though, it'll turn into full-on love again after you've gotten a break from it.

Full of What If's, self doubt, and a story that may or may not suck? Here are my notes:

• As I just mentioned, make notes. Whether it's tweaks you need to make to the story line or to details within the story, or maybe it's mistakes you make over and over again, make a "BEFORE YOU SUBMIT" list, and follow it every time. Spell check, double spaces, formatting, etc.
• Ever heard of the phrase: Two sets of eyes are better than one? Yeah, there's a reason that's a saying. Find someone you can trust to read and critique your work. Chances are, you're like me, and your brain auto-corrects words/sentences, so you could have really jacked up somewhere. A critique partner will help you catch those. 
• Read it out loud. I know, that sounds weird, and it can feel uncomfortable. If you can find some alone time, read your book out loud. This can help you improve flow, and sometimes you'll even catch those pesky mistypes I just mentioned. Chances are, if it reads well when you speak it, then you've nailed it.
• Don't write for someone else. Write for your characters. Write for you. Some people will like your book, some will hate it. Don't focus on those haters. For one, some people thrive by making others feel bad (aka: bullies). For another, you shouldn't waste a single breath on them because there are other, more important people to focus on: the people who love your book, those whose lives were changed by merely losing themselves in the story you brought to life.

And finally...
You can write. Your characters chose you, because you rock that much. Anyone who tells you otherwise can bite you.