Assess your student's language ability. Each student will have a different level of ability and, therefore, different needs. Knowing these shortcomings and needs is the vital first step in teaching around them.
Simplify your English. If a large part of the class is spoken, look to how you can simplify your sentence structures. The same can be said of reading exercises, questions and so on.
Produce a vocabulary sheet. Many students have a relatively good vocabulary but struggle with grammar and syntax. However, if you are teaching a subject with many specialized words, it would be a good idea to produce a simple glossary with pictures and simple explanations.
Use more visual indicators. Pictures and video clips are near universal. Your student will be able to glean a lot from the visual clues.
Give the student extra attention during class. If the class is working on a project, speak to your student and give a second, simpler explanation to smooth things along.
Pair the student up with another. Pick a student whom you feel will help the student with limited English ability.