Divide into foreground and background
Not everything in a page layout is equally important. As I mentioned in maxims of page layout, I think of documents as having a foreground, containing the most important elements, and a background, containing everything else. Typography communicates this distinction to the reader visually.
Yet lawyer letterhead often suffers from two problems. First, the address block (the background) dominates the page, upstaging the text of the letter (the foreground). Second, the foreground and background don’t relate to each other visually.