“Most people make the mistake of thinking design is what it looks like. People think it’s this veneer — that the designers are handed this box and told, ‘Make it look good!’ That’s not what we think design is. It’s not just what it looks like and feels like. Design is how it works.” - Steve Jobs
EDIT: That's one of my favorite Steve Jobs quotes. When I was younger and making my first web sites, I thought design was all about making things pretty. Turns out, pretty has almost nothing to do with design (and, in fact most of the design I like the most is aggressively minimal and stripped away). Design's about how things flow.
(I'd also say, speaking as somebody who takes a lot of interest in design, that this makes design incredibly fun once you figure this out. It means that every page you make, even sign-up pages, are wildly different and interesting. I've made something like 6 iterations of my site's log in page, simplifying and condensing it each time, and I get a thrill out of that similar to the one that comes from making code better and more elegant. Not to speak of the notadouche sign up page, which was very very fun to design.)
“Most people make the mistake of thinking design is what it looks like. People think it’s this veneer — that the designers are handed this box and told, ‘Make it look good!’ That’s not what we think design is. It’s not just what it looks like and feels like. Design is how it works.” - Steve Jobs
[edited formatting (thanks unalone)]