Know what you are teaching. Being a native English speaker does not automatically make you an effective ESL teacher. For non-native speakers, learning rules of grammar and pronunciation is crucial to effectively learning the language. As an ESL teacher, it is important that you refresh your own understanding of the topics you will be teaching. Prior to drafting your lesson plans, give yourself a quick refresher course on the basics of English grammar so that you yourself have a firm foundation.
Write up your own lesson plans for each class. Drafting a lesson plan prior to each class will help you prepare a well-thought out session for your students. Your lesson plans should remain simple and focused, with a variety of activities that incorporate student involvement. The creator of Teaching ESL to Adults (see References section) suggests that each lesson plan should have a main topic, a few objectives, time to explain and study the material as a class, student activities and a short evaluation at the end.
For example, one class session may cover the verb "to be." The objectives might include having students be able to effectively use the verb "to be" in a short conversation or in writing five sentences. After explaining the uses of "to be" and providing a few examples, students may write out a few sentences using the verb. Lastly, the teacher may evaluate these sentences to assess how the students are learning.
Start with the basics. If you think back to when you first started learning English in school, the first things that come to mind are the alphabet, pronunciation and basic verb structure. The same should follow for your students.
In explaining basic topics, do not overload your students. Teaching "horizontally" means that rather than building on the many uses, rules or exceptions of one topic ( i.e., the verb "to be"), start with one use at a time. In this case, instead of teaching the use of "to be" as a state of being and a way of expressing passive voice, just focus on the first part and cover the second part in the next lesson.
Enunciate clearly and speak slowly. Students who are just learning English will not be able to keep up if you are speaking with a heavy accent or speaking very quickly. Enunciate all of the letters in each word so they can be clearly distinguished from one another. Similarly, avoid "slang" English until you and your students have gone over such cultural idioms.
Acknowledge cultural differences. Some students may learn differently from each other and may have difficulties with or excel in very different topics. If students have recently emigrated from other countries they may be dealing with culture shock in addition to a language barrier. Try to be understanding of their unique struggle to learn both a new language and a new culture. Get to know your students as people and learn about where they come from as well. Knowing more about them will improve your teaching skills as you will have a better understanding of what each student needs from you.