I have to deal with graphic designers in my real life job and for my side projects. Unfortunately, people put too much faith in these static mockups, so lately I've been cautioning clients to not get too caried away with the images the designer slaps together. Granted, I'm no website developer expert, but I have found these guidelines to be true for the most part.
Website Design Guidelines
- The graphic design image will never look the same as the website. Once you've decided on the graphic design, just throw it away, and consider the website its own entity. Once the website looks
good, stop(Even if it doesn't look exactly like the original layout).
Try to use as few images as possible. see point 5 for more details.
Simple and readable sites are more usable than flashy and creative sites.
Certain design principles that make good images do not make good websites. Don't choose a layout simply based on looks. Check if other websites have used a similar layout, and what you thought of it.
Favor dynamic content to static content. Web pages and browsers are made to resize and scale. if all your site is composed of text, it scales great; but if it's hard coded images and banners, you're stuck.
Now, all of these guidelines get thrown out the window if the client is actually working with live HTML samples. I think 37signals hit the nail right on the head by working directly with the actual user interface from the get go.