All the answers on this topic have been great so far, I agree with them all!
My personal approach has always been:
- to get to know my students and what they are learning for (for conversation/travel/exams/writing skills/speaking skills etc.)
- to stay dedicated to the learning goals (pass exam, speak to a foreigner... whatever it may be)
- for my students to get to know me (if they like you and respect you, more get's done)
- to deviate from the textbook (to find reading, writing, exercises or games with different topics, especially more popular themes)
- to reward (age appropriate rewards; my adult classes enjoy having "free" discussion topics, watching a movie clip or discussing travel/music or culture issues. The children love story time where I read to them or the usual candy/sticker rewards or I would teach them an English song or nursery rhyme, anything loud and fun to say (Dr. Seuss works)
- to make sure my students and I are having fun with the lessons so that no matter how tired they are or how long their day has been they know I will be waiting for them, excited to see them and help them learn.