How can one ensure that the style guide is maintained and used?

Question

How can one ensure that the style guide is maintained and used?

I'm specifically working with UX styleguides.

Answer 1

The best way to keep a style guide up to date and widely used in the organisation is to make it as a Living style guide, following a Styleguide Driven Development approach in the product development process.

Here are a few definitions of those two terms:

Living style guide definitions:

“A design showcase built using live presentation codebase.”
— Chris LoPresto at EmberConf 2016 ▶️ [7'00"]

“A reference for a team of designers and developers to understand how an application will look and feel.”
— Patrick Hildebrandt in What Is a Living Style Guide?

“A living document of code, which details all the various elements and coded modules of your site or application.”
— Susan Robertson in Creating Style Guides

“A live version of a brand style guide.”
“Living style guides are something that should be developed with every project”
— Brian Eye in Night of the Living Style Guide

“An important tool for web development today, especially in large, complex web applications.”
— Steven Lambert in Creating A Living Style Guide: A Case Study

“A documentation of UI elements and patterns collected from a site or application with the purpose to allow developers to use consistent styles across their whole project.”
— Nancy Young in Ten Living Style Guide Tools for Web Designers – Best of

Styleguide Driven Development definitions:

“Is the practice of using the styleguide as the focal point for all front-end UI development tasks”
— Matt Fordham in Styleguide Driven Development at Seattle Interactive Conference 2014

“A practice that encourages the separation of UX, Design & Frontend from Backend concerns. This is achieved by developing the UI separately in a styleguide.”
— Jordan Lewis in We build Envato: Styleguide Driven Development

If you need to go deeper on how to implement a Styleguide Driven Development process in your organisation, a simple search on YouTube will bring you a few good presentations.

To finish, a very good example of style guide that implements these concepts is the lonely planet style guide. They even wrote a very good article about why and how they built it: A Maintainable Style Guide

Answer 2

To be maintained a style guide needs to be online as a blog or a wiki. To be used a style guide must be based on principles rather than on rules to be a guide and not a break.