If you are going to design Internet or collaboration portal you will be developing some master pages and page layouts for sure. here are some of the guidelines you can use to develop them.
If you dont know about master pages and page layouts then Master pages and page layouts dictate the overall look and feel of your SharePoint site. Master pages contain controls that are shared across multiple page layouts, such as navigation, search, or language-preference for multilingual sites. Page layouts contain field controls and Web Parts. The following figure shows how page layouts and master pages work together to create the layout for a Web page
To Read about the approaches of Creating masterpages and Page layouts please read
Summary: Learn two ways in which developers and designers can create Microsoft ASP.NET 2.0 master pages that define a site’s global appearance and to create page layouts that define the rendering of specific content pages in Microsoft Office SharePoint Sever 2007 publishing sites. (9 printed pages)