Make the mockup in markup
Interesting Info
Meagan Fisher makes a strong case for changing the methodology behind how a web designer designs a web site.
Basically, the most designers will create a series of pictures of various pages of the new site in Photoshop, and then once approved, undertake the process of creating the markup (HTML, CSS, etc.) from the idealized picture.
She suggests instead that building the mockups directly in HTML and CSS is a cleaner, faster, more accurate way to proceed.