This community surprises me. You guys really know your stuff, and you're not a bunch of jokers that like to troll the hell out of each other till they cry.
Due to this, I'm interested in a different level of opinion; what is your favorite SEO technique? Why is this one technique your favorite?
And it can be for any reason. It could be because it's the most fun for you, it could be because you find it the most effective for what you do, it could even be because you just like the idea of it... it doesn't even have to work really well, you just have to like it, and I want to know why!
EDIT: and I want ONE technique, ONE tactic that you implement in the vast world of SEO that just really hits home in your heart and mind. I don't want a gigantic strategy, I just want one small (or big) thing you do that is SEO related that you really like.
It could be as simple as figuring out where you want your <h> tags for your page, and adding them. It could be the complex art of link-building.