Hold high but realistic expectations for your students.

"Research has shown that an instructor’s expectations have a powerful effect on students’ performance. If you treat your students like motivated, hardworking, and independent learners, they are more likely to behave that way. Try to set standards that are high enough to motivate students to do their best but not so high that students will feel that the goals are beyond their abilities. Students need to believe that meaningful achievement is within their grasp, and they need early opportunities for success."

Source: Tools for Teaching, Davis, BG, 2009