THUNDERCATS!!!!!
now that that's out of my system....
Really, what are you looking for? Whatever way works for you is the most efficient way. If you are a more code then worry about looks, do your code first. If it's easier for you to design and then code around your design, do that.
Me personally, I do both at the same time. I get a basic idea in my head, scribble it down on paper. Then, I run through different scenarios and what I'm going to need. I come up with a pseudo style-sheet, and start to code using some standards of my own (like the content wrapper is cwrap and so forth). When I get bored of coding, I do design. When I bore of design, I code. It's not the most efficient (like doing all at once) but it keeps me interested and I get it done (eventually).
It really is a personal preference thing, and no-one can really tell you what the most-efficient way to develop a site is. Main reason is because everyones mind works differently, and you may like to design the basic format, and work out intricacies later, or maybe you like to get navigation out of the way because that's the hardest. Or maybe you start easy and go to hard... who knows.
Best advice I can give you:
Sit down, and think about your strengths. Put that up there first. If your strength is coding, and your weakness is designing, get the code down first. Then, when that's done, you can focus all your energy into designing. You don't need bad design mucking up your coding brain... could cause some mucky code...
