I was catching up on some of my assignment's reading when wham! Just like that, I stopped mid-page. And not because Sally the crazy dog was up to her old tricks. But I did learn an old trick or two.
The writer was going on about external conflicts (Terribly important to a story, but we already know that, don't we?) and internal conflicts (Terribly important, too, if you want to make things interesting). Then I read a few lines on the importance of characters having a flaw or two so that they're not these perfect little people that, deep down, (or maybe not so deep down) we'll end up hating. Hold on now, I'm just about to get to the point.
And here it is: if your character doesn't have a flaw or two, how can he learn or change? Which is terribly, terribly important to a good story.
Let's consider good, old Harry P. (just as a for instance) and his constant (external) conflict with bad old Voldewhatever. Now consider all the flaws Harry had, like his insecurity about being a Muggle and being so different and just in general being a real pain in the whiny neck (those would be the internal conflicts). But it was all those flaws that made Harry so appealing to kids. He was an unlikely hero, with several obnoxious behaviors common to the typical 12 year old. But didn't he learn quite alot along the way? (Frankly, he had to learn the same thing more than once, but that's another story.) And didn't he change, besides getting facial hair and body odor?
Give your protagonist a good flaw or two and then sit back and watch the conflicts bring your story to life. Your protagonist must learn something and then use that knowledge to effect an internal change. That's the trick for the day. And maybe just that one little bit will make all the difference!