There's not much for us to teach tweens directly, instead the wise parent learns to LISTEN.
Tweens need their loving connection with us more than ever. We can stay close (or develop closeness if it's disappeared) by listening deeply to what they talk about. If your tween seems interested in superficial things and that worries you, remember that there's a lot under the surface! Transform your conversations from passively letting them chatter about Minecraft, fashion, or a band into developing a genuine interest in what they think about those topics.
When we listen and cultivate real connection with their interests, we allow them to lead us into the heart of their lives. They begin to share their beliefs, struggles, and big questions. The key to this is to listen without judgment and stay curious and present. Basically mindfulness, right? So if you aren't yet practicing mindfulness, do it! It will definitely help you to parent your tween.
The second aspect, as with every age, is to be a leader, providing firm and clear boundaries. A leader doesn't get into power struggles and doesn't lecture. If you are battling with your tween, step back and find a more dignified stance. Discern which issues are the very most important and which you can have an influence on. Let go of things that do not fall into both of those categories! You aren't (and shouldn't be) in charge of who their friends are, what they want to do with their lives, or which sports they want to play.
Tweens want and need our love, our connection, and our guidance. They also want and need our respect!
As a mom (to 2 teenage sons), wife, and person in the world, I have been on a long imperfect journey. I have made many mistakes, but with mindfulness, emotional reflection, and lots of support I have learned enormously from those mistakes.