I go to PR China every summer to teach Chinese students (see UCAS advice) and have taught English to many students privately, including a range of abilities and ages, and several students for whom English was not their first language.
I teach two courses at the University of Bristol: study skills on the Foundation Year in Humanities (I also offer UCAS advice to these students), and the transition to long essays on the BA English Literature and Continuing Education.
The students on both of these courses are all returning to education after a long gap (several decades for some) and can range in age from their early twenties to pensioners. Such a mixed group makes peculiar demands on the teaching staff, but they are enormously rewarding to teach and have helped me improve as a teacher. In my first year teaching on the Foundation Year (2012-2013), I received the best student feedback, despite teaching alongside much more experienced colleagues. In 2013-2014 I supervised a dissertation on race and literature and ran additional sessions for a smaller group of Foundation Year students who applied to university through UCAS (see UCAS advice), all five of whom were accepted into their first choice universities.