In my early days, almost completely from books.
Now, I’d say almost 100% from websites to get the
latest CSS tips and tricks.
For design ideas I have a few favorite websites
that showcase some of the best designs out there. I grab
screen shots of my favorites, print them out, and study them
like a fiend.
I also subscribe to an online magazine called "Before and After"
It’s not only about site design, but for print as well.