Branch for browsers where possible. You can use server-side scripting to check for browsers. If you have an international audience, also consider adding language options. Say you're using the 256-color palette to design your graphics and they look great on your system. You can provide information to readers who are browsing with graphics turned off.
Internet Explorer formats the page with text first and adds the graphics later.
If you don't specify the size of your graphic, the browser will have to reformat your page when it downloads the graphic and obtains that information. This results in an annoying screen flicker. Try to provide text-only navigation. Instead of alienating these users, be sure to provide text elements for navigation. Say you have a graphical navigation bar.