Dreamwidth style system discussion

HI
I'm new here and would like some advice/help in designing a layout for my journal.
Somewhat familiar with CSS and learning more about it everyday.
I've been looking at several layouts here at DW, very, very nice designs.
I'm going to be doing web page design for my own computer consulting business in the future and am taking a course in the Spring. Have some knowledge of html.
I often read the the source codes on webpages to get some ideas... ;)
I'd also like to design some mood themes too.
Where does one do that? Here?
Thanks! :D

edit: Saw the links here. Going to take a very close look at those.

Would also like to hear from people here how long it took them to design a layout and any tips would be very helpful.

Those links for the Tabula Rasa, etc. are very, very helpful.

Thanks again! :)