once you know how to use the tools, it is good to learn some theory... for layouts check out Grid Systems in Graphic Design, it gives you a very Swiss approach for building a grid and then fitting content to it.

Khoi Vinh is another guy to look up, he heads up design for nytimes.com and is a huge proponent of using grids his site is www.subtraction.com

Also, learn about typography. Elements of Typographic Style is supposed to be best.