I've been doing it for a while. Taught all the age sectors (very young learners, young learners, tweens, teens, university students, adults, business/corporate English) in both major context types (EFL and ESL). Had coursebooks published. Been privileged enough to have a lot of teachers ask me questions (which in turn have always forced me to ask myself questions).
It really comes down to these seven things.
1. Students are people
Get to know them if you want them to get to know the language. Listen and watch more than you tell and monitor -- it's the only way to really get to know people and group dynamics. Your 'teaching skills' aren't worth the paper they are written on if you can't develop people skills and group leadership skills.
2. People have the capacity to teach themselves much more than you can teach them
Paving the way for students to become independent, resourceful and experimental should be your primary goal. Each and every one of them represents an enormous well of potential. If, at the end of a course (or even a month) you're still seeing them as trunks and not getting (and giving them) a feel for the potential of their root systems, you've wasted their (and your) time.
3. Know the language by constantly re-learning it
And I mean really KNOW it. It doesn't matter if you are a native speaker -- all good English teachers need to be willing to re-learn the language on a constant basis. Explore how it works. Notice patterns. Enquiry is often more productive than inquiry. The very best English teachers I've worked with emerge from almost every lesson talking about something new they've learned or noticed about themselves and the language and students they are teaching. Even after 10 years in the job...
4. Try stuff
Experiment as much as you can. Don't ever stop trying new ways to do and discover things. The day you decide you 'know' enough (whether as 'expert' or as 'cruise-moder') to not need to keep trying out new things is the first official day of your teacher rot.
5. Build up a really big bag of tricks that can fit in your pocket
Back in my teenage D&D roleplaying game days, we used to refer to it as a bag of holding. It was a little sack that, with a magical twist, had an almost unlimited carrying and storage capacity. You could carry the contents of your whole house around in it. The language teacher's bag of holding needs to be constantly added to, but the contents also need to checked and organised on a regular basis (just like our memory banks, I suppose). It's okay (and in many situations, good) to use coursebooks, but not if you're not learning from them, picking them clean of all useful activity types and methods for you to use in your own way at some stage further down the line.
6. Teacher development needs to be glocal (local + global)
The staffroom is a precious resource, and not because of what's stacked on the bookshelves there. Listen. Talk. Ask. Share. But you also need to get out and about and regularly check in on and contribute to what's happening in language teaching around the world. Web 2.0 has made this sort of connection capacity both unlimited but also as potentially personable as the interactions in the local staffroom. I've met many good/nice teachers who never went on to become great teachers because one or the other was missing in their personal learning network.
7. Enjoy it
If you're not enjoying it, your students sure as hell aren't enjoying it, either. When it starts to slip into unenjoyable, drop everything and concentrate on making it enjoyable again. And if you can't (despite a genuine, long-term effort) enjoy it, get out of it. Give your prospective students the chance of having a person who enjoys what they do, and give yourself the chance to find something else you do enjoy.
As I've said in the title of this post, it's not rocket science, really. But it does have a heck of a lot to do with frame of mind.
=D
