Whenever you have more than one person creating communications materials for an organization, it helps to have a guide outlining the styles and design standards for the brand.
Contrary to what many amateur designers believe, consistency is good. You don’t want every piece of marketing collateral to have a fresh and unique look from the others. Strong brands have consistent and recognizable styles. Most Americans can identify an Apple product by the box from 50 feet away. Always the same colors, fonts, and style. You never see Apple marketing materials with plaid backgrounds. Never.
The style guide defines the standard logos, fonts, and colors used by your brand. It outlines the design elements – backgrounds, margins, logo spacing etc, to allow a consistent visual look between marketing materials.
Effective style guides can be though of as cookbooks rather than rule books. Instead of a “Thou Shalt Not” tone, it should take a “Here is how to do it” voice. When developing style guides, include the reasoning for style rules whenever possible to help users understand why the standards exist. That will help them follow the intent when they are faced with design issues not covered by the guide.
Most style guides are only 3 to 4 pages. When combined with a set of style-compliant templates, the style guide can help new content developers create consistent materials with minimum effort.
Don’t try to develop a comprehensive guide all at the same time. Just start by documenting the basics, include some examples and templates, and let the guide grow over time. If you wait until you have all the answers, you will probably never get started.
Long term, a simple style guide will reduce your development time and improve design consistency, strengthing your brand in the outside world.