Why does nobody ever mention HTML Dog? I learned all the basics the right way reading from it, the ideas behind them, and what to avoid. It's a seriously great website (and formerly a book, I think? I was a penniless teenager back when I read it), serving as both a tutorial and reference, and it's been around for a really long time.

http://www.htmldog.com/

For everything else, there's http://www.quirksmode.org/ and Stack Overflow ;)