Matt, I understand exactly what you mean as I've struggled with the same in the past. My problem was mainly that I focused entirely too much on myself and the way I looked and could pick out certain things that I did not like. Now, for you this could be anything...clothes, hair, or anything dealing with appearance; personality, attitude, whatever.
Take the appearance for example. Say you think your hair sucks, or whatever. Maybe it's too poofy or frizzy and all the gel in the world cannot fix that without making you look like you're trying too hard. You're gonna fret over that until you get it right most likely. What I did with something like that was try to pick out a poofy or frizzy-haired dude...one whose hair isn't meant to be frizzy or poofy. Okay, find another one, and a few more. Notice that even though you might be at that point focusing on their hair, if you weren't looking for it, you wouldn't notice. Chances are, unless it's absolutely horrendous, you aren't gonna notice it, and neither is anyone else. If a girl looks good, she looks good regardless of whether or not she's having a bad hair day. It's the same with guys.
My point is that whatever you are insecure about, just take a look at someone else. Chances are, if you aren't looking for it, you aren't gonna notice. The smallest details that you worry about are probably way too miniscule for anyone else to notice unless they're just out to be critical of someone (and those peoples' opinions should be forever excluded from your mind because they mean nothing).
And remember, although too much self-concern is bad, as is too much of anything, there is nothing at all wrong with self-consciousness. We should all be conscious of self if we're going to better ourselves. Narcissism is just the word that describes the wholly self-absorbed state. Don't think you're wrong for focusing primarily on yourself; just don't let it get out of hand.