Show yourself, sell yourself.

So, you've finished your book.

Yeah, it kinda feels just like this.

It's been formatted and edited to a fine sheen, it's nearly perfect. Your cover is a surefire attention grabber. All is well, and you're ready to promote the ever-loving hell out of it. It's time to Rock. And Roll. All night long.
But hold up just a minute there, kid. You're not quite done yet. There's work yet to do, and it's gonna be a hell of a lot harder than convincing people to read your book.
Every successful product needs a brand name to instill trust in the customer, and in the literary world, that brand name is YOU. The Author.

This picture pretty much sums up your reaction, I bet.

That's right, not only do you have to thrust your book into the spotlight, you gotta be in there too. And to many Authors, fresh or seasoned, this idea is as terrifying as anything Lovecraft could ever imagine.

Generally speaking, Authors are a shy bunch for a variety of reasons. You can test this theory by simply looking at some Author's Facebook Profile Pictures. Note how many use pictures of animals, celebrities, cartoon characters, damn near everything but their actual face?
Honestly, if you're doing this, just stop.

It doesn't matter how good it is, nobody wants to read a book written by a chicken.

If you want people to take you (and your work) seriously, you need to show them the 'real' you, warts and all. You may not feel you're photogenic enough, and you may be right, but how many of us are?
Unless you're Michael Ness, that is.

Hello Ladies.

Seriously, look at this guy. Ridiculously Photogenic Author Guy indeed. That's some daunting shit for most of us right there, but your face is your logo for your name brand. You need to show it, readers like a face to associate with the book.
Another point to consider is that if you're going to use your own picture, choose carefully. Not just any old picture will do. You'll want to choose an existing picture, or even take a new one that portrays you as a representative of whatever genre you write in. For instance, if you write Erotica, don't use something like this:

Hello? Ladies?

Probably not the image you're going for, is it? Get a razor, get rid of the camo, and clean it up. On the same page, if you write Horror, don't use a picture with you smiling in unbridled bliss at the beach.

So now you've chosen a good visual representation of yourself and your work, you're all done, right?
No. Sit back down, we're not done quite yet.
You may be familiar with the recent Chelsea Cain flustercluck. If not, here's a quick recap:
She recently went 'full retard', and lambasted her own fans for 'asking stupid questions'. She quickly recanted when she was spanked by her publisher for being an idiot, and went ahead and pretty much said the same thing again, but in a slightly different way. She lost a LOT of current fans, and alienated many more potential readers because of it.
Handy Hint? Don't EVER do anything like that. It's like shooting your writing career straight in the face.
Although at times it may be tough, but since you're the 'face' of your product, you have to maintain some sort of professional decorum pretty much at all times. I'm not saying you have to be a suck-up ass kisser to your fans, but damn it, don't be an asshole when fans want to interact with you and dare to ask questions you may feel are stupid. Logically if you treat them like unworthy crap you scrape off of your shoe, eventually no one will want to read the book you worked so hard to put out, and you'll end up wallowing in a pit of nothingness that you yourself dug. Without readers, an Author has no purpose. Always remember that.