As a teacher, How would you prepare your first day classroom?

prepare your home work about the subject , than enter in class room  and make a friendly environment.  

I never took my class light so I always get in the class well prepared. No matter it is my first day or I'm a seasoned teacher. 

The things to do on the first day in class for a professional teacher are listed below:

1- Excellent preparation of the subject.

2- Well dressed and decent looking as first impression is the last impression.

3- Introduce yourself and have an introduction of the students.

4- Initial talk about your way of teaching, how the students should follow and how to reach to a common goal.

5- A few words about required decorum of the class are very beneficial. 

6- A general discussion about your subject in the class gives you the idea about grasp of the students on this subject.

7- Always try to present your friendly disposition but never neglect the rules.

arrange the sitting in the way I like and it should be " u" shape and then tell pupils about the constitution of the class , instructions and rules that should be followed besides introducing myself and my students to one another.I can also tell students how simple and useful the subject is.

I am not a school teacher, so I use regular college rooms

I agrre with the answer added by MR anayat bukhari

Fun and work - so I work