Be prepared and when you make mistakes, own up to it and explain how you are going to correct it. 

I learned to remain calm and give students a chance to explain their disruptive behavior. 

I learned the first step in dealing with unfocused students is to look at how you're handling the situation and evaluate if there are any changes you need to make as an instructor before automatically thinking it is the students that need to change. 

Be clear when explaining the syllabus and expectations. 

Use a variety of teaching and learning techniques to keep students engaged. When demonstrating skills, practice first, try to keep it to 5-7 steps, and have a backup in case the demonstration does not go as planned. 

Really try to learn their names. Be personable when introducing yourself. Let them know your experience and achievements which can show them things they could also attain in the future. Also let them know what you like to do in your spare time so you can be relatable, making them less nervous around you. 

Being prepared, organized, personable, and a clear communicator goes a long way. Being these things sets the tone and shows the class you are invested and care for their success. 

Remember your previous instructors when you were a student and why they were great leaders and use and incorporate those qualities into your teaching style.