Certainly nothing new (it's from 2014), but this is a very comprehensive article about writing great commit messages.
- Separate subject from body with a blank line
- Limit the subject line to 50 characters
- Capitalize the subject line
- Do not end the subject line with a period
- Use the imperative mood in the subject line
- Wrap the body at 72 characters
- Use the body to explain what and why vs. how
Also, I like the way how Chris runs his blog from a public Github repository and apparently accepts pull requests on his posts (just click on the revision link on the post).