If you are writing for the elderly, use a larger type size. Avoid making lines of type too long or too short. Use one inch side margins to get a line length of 50-70 characters. Use white space in the margins and between sections. Avoid using capital letters.
Capital letters are harder to read.
How to Write Organizing paragraphs Use one idea per paragraph to emphasize each important concept. Start each paragraph with a strong topic sentence. Use examples to clarify ideas with which the reader may not have had experience. Avoid complex sentence structure and long, fact-laden sentences. Use the active rather than the passive voice.