Some useful insight here from Angela Moore writing on the excellent Scroll blog. If you've ever needed a style guide or you have one and no one uses it, this is a really good place to start. Allow me to share a tip of my own. It sounds silly, but there is one style guide of mine that got used the most. I knew it would make a huge impact if everyone embraced it, but there was low digital maturity in the team. So I printed hard copies out and put them on everyone's desks. It worked because they could see it right there in front of them and watch each other use it as a reference document. Within a few months, they were adding new stuff to the guide themselves and gradually we all moved to the digital version, which was collectively kept up to date. Win!

YouTube video by BBC Archive