In order to effectively teach someone to speak English, you have to know something about how they learn. You might want to first familiarize yourself with their culture and background. If you can, try to have a direct and not second-hand experience, as well. This is important as many native English speakers tend to view language in simple contrasts. If something is “mine,” then it cannot be “yours,” for example. Many non-native speakers tend to learn in a more alternate and even pluralistic fashion. For example, in many other cultures, the idea of individual possession does not even exist.
Make periodic lists. Encourage students to make a list of situations or opportunities in which they may believe it might be a good idea to speak English. Gather up these initial lists and refer to them later. The idea here is to see if students take advantage of potential opportunities when they present themselves.
Get them listening. If you want to effectively teach someone to speak English, try to improve their listening skills. Introduce them to the concept of active listening by performing "paying attention" exercises. It may sound a little silly, but speaking English is a lot more than just understanding words, too. Learning context is a large portion of effectively communication.
Get them talking. Have a student speak aloud as often as possible and be sure to let them know it is fine if they feel the need to repeat things over and over, as well.
Teach them how to guess. In some circumstances, native English speakers might have to guess or infer what another person has said to them. One such example is when people have to guess at a word they do not know or recognize. Native English speakers are able to do this because they learn certain non-verbal cues from parents or caregivers as children. Someone can learn to speak English by being taught certain relational cues between speakers, as well.
Invent new words or phrases, if necessary. Often times when a non-native English speaker finds they are engaged in a conversation that is unfamiliar to them, they will refuse to speak entirely for fear of humiliation or embarrassment. Rather than have them simply be at a loss for words, have them practice describing scenarios in English, even invent new phrases. If they cannot remember the word for "elevator," have them remember to say "moving box, up and down." If they cannot remember the word for "lolipop," have them say "candy on a stick," for example.