I have found one new tip of quick class-wide assessment that would be really helpful for my teaching, which is 

"Placing the answers at different places in the room, and let students point at the correct answer"

I usually use yes/no answer or the thumbs up reaction to get their response. I think letting the students point the answer at the correct corner would make more interaction, making the class more active and fun.

There is one routine that I use in every class that I teach. That is starting the class with a greeting song or sometimes by asking some questions first and doing the rain clap. When I lead the song, I sing with full of energy and give friendly smile, making the students feel comfortable with me.