Someone told me trial and error but I think that would be too hard. Don't recommend w3schools or codeacademy thanks.
I recommend you buy Sitepoint books. You can get print editions or PDF downloads.
W3Schools gave me a start as far as structure (yes, I know you said not to recommend them...)
Otherwise, I just Google stuff as I go or watch videos on YouTube that incorporate a lot of CSS and have a good commentator in the background.