Proper attribution quotes in dialogue

I was working on my new book and realized that I didn't know how to punctuate dialog attributions: you know, the "he saids" and "she saids" that tell you who said what. It turns out that a lot of what I've written, pretty much my whole life, had been punctuated incorrectly.

For example I'd write something like:

"Are you going to the store?" Asked Sam.

That's wrong. It should be 

"Are you going to the store?" asked Sam.

I like this article enough to recommend it.

That's some of the random s*&# I learned today.