It doesn't matter if you're building web apps, mini-sites, doing PPC marketing, one thing is certain: you'll never be perfect at it.
I'm a big believer in learning by doing. You can keep reading blogs (like this one), but without any action, you're just wasting your time.
This is my favorite quote of all time and its a fairly recent one by Seth Godin. To be honest, I never even read his blog until I saw this. But after reading the following I was hooked:
Anxiety is nothing...but repeatedly re-experiencing failure in advance. What a waste.