Ugh, using this phrase makes me cringe! All too frequently, too many people come up with what they consider to be best practice when talking about subject X or topic Y.
This said, there are some useful tips we can use when creating media queries; they aren't just about following best practice, but equally making things easier for ourselves, so that we can display the right content on the right device at the right time:
Always start small when designing media queries. This will avoid browsers downloading unnecessary elements that are only needed for larger screen sizes. Starting large is possible, but often requires some heavy reduction of content and is not likely to be as easy to manage.
When designing queries, don't immediately think you have to include everything from the desktop site on a mobile device. Sometimes it doesn't make sense to do so. More often than not, there simply isn't space or bandwidth to do so! It's important to consider the context of the site...