Prototyping in Photoshop
I will usually prototype a Web page in Photoshop or Illustrator where I can use the layers to show or hide alternative elements, moving them about the page until I get a 'look' that I am happy with. Having done that, I will produce the final images in GIF or JPEG format before taking them across to Macromedia's DreamWeaver/BBEdit for assembly and coding.
I will then 'publish' the pages using Apple's Web Sharing control panel so that I can see what they look like in Netscape and Ms Internet Explorer version 3 and 4 on my PC. I expect a considerable amount of fine-tuning to be done at this stage. Each browser has it's own idiosyncrasies - I tend not to use browser specific features but there are usually unforeseen problems to be sorted out.