See the classroom, and lesson, from the students' point-of-view.
I think this is a fundamental thing, and it's a rule that I live by day in, day out. Perhaps it stems from Atticus Finch, perhaps it doesn't. All I know is that I cannot plan, deliver or reflect on a lesson without placing myself into the shoes of a student who had to endure it. They are our customers, in the broadest sense of the word, and their experience matters. I am under no illusions, though. I know that their viewpoint can be flawed, or short-sighted, and there is more to this than simply making lessons fun or silly. No, this extends into really focusing on how they will be, are, or have been learning. How will they react to this PowerPoint slide? Will the colours aid their understanding? Should I explain this concept in three different ways, over the lesson, using different analogies each time for different students? Can they understand this concept without certain key vocabulary? Is there any way I can exemplify this skill in a way they can grasp and enjoy? Above all, how can I make their learning easier, more enjoyable and more seamless? These questions are always on my mind, and I am forever wondering how they are likely to react to what I'm giving them. I think this is absolutely vital, and would recommend this simple technique to anyone.
It also leads to removing all busywork from lessons. Occasionally I will set work like this, especially with KS3, but it always makes me feel awful afterwards, like gorging on a pizza covered in chocolate and chorizo. We've all had days where we're ill and lack the energy to bounce around the room like a crazed educating frog; typically we react to these days by giving them work where time-consumption seems to be the main factor. But equally, we've all felt that hollow sense of worthlessness that stems from this work. As I can't abide this feeling, I avoid busy work like the plague, and ruthlessly over-analyse any set task in a lesson just in case it has elements of busy work within it. This can be more a curse than a blessing at times, but it seems to work well.
Behaviour management also connects with this. Have you ever told a student off, knowing full well you're being unreasonable and probably a bit of a prick? I certainly have, and can't face it. I have to know that I'm being totally fair, otherwise I find myself blustering like a moron and, viewing myself briefly from their point of view, I realise what an insufferably foolish goon I look. Teaching two boy-only groups has taught me that being consistent, reasonable and willing to let things go is the only way to succeed with just about any child, let alone misanthropic male teens. These days I always ask myself, am I actually correct? Have I fully explained why there is a problem? Have I made it crystal clear what the potential repercussions will be? These self-checks tend to work pretty well, and I hope I don't come across as a frustrated, bellowing cow-person anymore.
Maybe it's an obvious thing, but I know I was never taught to look at a class from the customer's viewpoint during my PGCE. I think it's very helpful, and reckon that it keeps me sane in an increasingly insane educational world.