What should be the first concern of a teacher of English or any other language? I would state that he himself.
He has to embark in a continuous process of learning English, if English is a foreign language.
Besides he, inadvertently, will pass on his concern to his students.
At present I’m reading again the first sequel of the Harry Potter series, and I find motives and reasons for delighting with the reading. For example today I learned ‘ruffled’ amongst other words. This word can help me on some post. / Photo from: mortadelo and filemón are two Spanish famous comics characters, from many years ago