Help your students master the basics. Teach the Indonesian alphabet, character by character, demonstrating the pronunciation of each letter in a slow and clear manner. Encourage the students to repeat the letters after you until they are able to confidently recite the whole alphabet.
Introduce the students to useful phrases in Indonesian. Start with key phrases such as "good morning," "thank you," and "Do you speak English?". Mastering these at an early stage will give the students an important sense of achievement. Divide the class into pairs and encourage them to initiate short dialogs with each other using the phrases you have taught.
Teach the fundamental elements of Indonesian grammar. Start with simple concepts such as the use of suffixes and affixes to form new words and progress to more complex ideas such as the active and passive tenses. Introduce new grammatical rules one at a time, ensuring that every student in the class has grasped the new idea, before moving on to something else.
Use multimedia resources to make your lessons fun. Playing videos or pop music in the Indonesian language can help to motivate the students and gives them an opportunity to experience the language being used in practice. Choose media that will appeal to the students you are teaching so that they will engage with it and absorb new vocabulary in the process.
Expose your students to the Indonesian language as much as possible. Once they have progressed beyond the stage of beginners, use as little English during lessons as possible to encourage the use of Indonesian. Organize group activities and games so that the students have the opportunity to practice speaking what they have learned in a fun environment.