Robin Williams (author of The Mac is not a Typewriter, not the comedian) has written many entry-level books about design, and this is probably the most universal. It explains not just the how of good design, but also the why -- why certain lines, shapes, and fonts combine together well to convey a message and why others don't. It's not a "how to be a great graphic designer" guide, but takes you through the most basic elements of design and how you can use them to create a better term paper, a résumé, a Web site, a newsletter, all the print and digital media that you use on a regular basis.
This book will make you a better noder. I am not kidding. If you think that trivial things like whitespace and capitalization, bold and italic, indentation and justification aren't a big deal, then you need to see the examples Robin presents in this book. Principles that she teaches will help you structure your writeups so that they're easier to read, scan, and understand. Anywhere that you use text, you can use this book.
And for all this, it's only $12 to buy. It'll be one of the best investments you ever made as a writer.