A teacher can improve students' speaking skills by insisting that classroom conversations always be conducted in Spanish. The teacher should set the example by never speaking English herself, feigning incomprehension when students ask questions in English and quickly quashing English conversations between students. Choosing practice activities that control the scope of vocabulary necessary to complete the task prevents frustrated students from switching to English. This is especially important for beginners, whose practice should be limited to short conversations focused directly on the target vocabulary. This way, students gain confidence in their ability to communicate purely in Spanish. As their vocabulary improves, speaking activities will become more complex and flexible.
To prevent students from speaking like robots, model where to put stress in statements, questions and exclamations. Teach students what word combinations are frequently pronounced together, such as pronouncing "¿Dónde está?" as "¿Dondestá?". Students can practice intonation by performing memorized dialogues in front of the class. Acting and performing give students license to ham it up, exaggerating the accents and intonation that you are targeting. In addition to writing their own dialogues, students can also memorize scenes from films and mimic the actors' pronunciation. (YouTube provides a wealth of video clips for students to choose from.)
Communication favors those willing to take risks with vocabulary and try out new sentence constructions. Either in a private conference or in front of the class, give a student a topic or a picture to describe and have him speak on that theme for an allotted period of time. The focus should not be on accuracy or presentation, but on generating original sentences on the spot. Don't give any feedback or corrections while the student is speaking. Instead, choose one or two relevant points to discuss when the student has finished speaking. This activity can also be done in pairs as an improvised dialogue.
"Intercambios" or language exchanges are an excellent way to practice listening and speaking comprehension with a native speaker. If there is no pool of native Spanish speakers in your area looking to practice their English, you can use a webcam to team up with a classroom in another country via Skype. You can also set up mini "intercambios" by going on field trips to the local Latin foods market or Mexican restaurant. Let the business know in advance that you're coming, and ask them to conduct the transactions with the students in Spanish.