Don't be afraid to own and apologize for your mistakes. Teachers often expect perfection- that should never the be the goal for themselves or for their students! Making mistakes is part of the learning process; modeling for students how to recover, adapt, and move on after making a mistake is a powerful learning experience.
Also, keeping a neat and tidy workspace shows students that you care about your work. When the teacher is messy or disorganized, students have a harder time trusting them with assignments, grading, attendance, etc.