THIS ANSWER IS FOR THE NON-DEVELOPER ONLY, so take this into account before you vote me down. Most everyone on this website is farther advanced than us in the tech department though wanted to publish this response for the few that may find this handy, due to also being severely tech challenged. JFYI.
For our Drupal Websites:
We currently have a 3-stage process only as this is what we have found that works "for us!" I am not suggesting anyone follow this either, I just wanted to share what works for us.
To start, I am one of the designers, though again not agile with development, therefore I create everything in a simple MS Word Document, with pics and all. I utilize the "draw boxes" option often. Then, this is forwarded to our primary web-manager/developer, who will either implement the changes, "or" if heavy programming is needed, will do an Adobe Photo Shop with the HTML slices, and forward to a guy who only does the heavy Drupal Theming and Creative for us.
For WordPress Websites:
WordPress Blogs are far less complicated, the learning curve less steep, therefore everything created is done "live" so to speak. If it looks good I hit publish, if I need some advice I make a telephone call, though have never needed much intercession from a heavy developer. Having said that, our banner & logo were created in MS Word and then the logo maker took it from there.
This is again, only for those that are in my boat, hopelessly developer handicapped!