Things like an activity for the minute the children step in the classroom to 'hook' them in and stop opportunity to mess about, a clear classroom routine, asking for silence then waiting and looking at those who aren't listening rather than shouting over pupils, short and simple rules with consistent consequences, an equal amount of praise as punishment, giving the easily distracted child the sheets to hand out to keep them occupied, if a child is speaking when you are explaining a task simply walk to their desk and put your hand on their desk then continue speaking (sometimes silence is far more powerful than shouting). There are lots of little 'tricks'.
I completely agree with you.
However, and I am not saying this applies to the OP, I have worked in a school, not now thankfully, where such 'tricks' would be meaningless. As a 22 year old NQT, I had lovingly decorated my classroom with posters, plants and pictures. My very first lesson, with a hook activity, worksheets on desks, rules up on the board clearly and lots of praise as the children walked in, was ruined in seconds when two boys walked in, made a paper plane from their worksheets, then threw my plants out of the window when I wrote their names on the board.
I lasted a year in that school. Kids would openly swear and mock you, walk out of lessons, insult one another and you, steal pens and books, trash classrooms and refuse to do really basic stuff like remove coats. It wasn't my bad teaching either - I did very well as soon as I left that school and I have now had several promotions and work as an assistant headteacher where, fairly ironically, one of my roles is to mentor NQTs!
If I had an NQT who was shouting I would want to support them and help them follow the school system, but the point is we have a system and we keep to it. I don't think some parents and some teachers for that matter appreciate just how "bad" some bad behaviour can be - it isn't just chatting over a teacher, not doing homework or turning up late to a lesson. It can be nasty, sustained and arrogant and it can be physically frightening too.
I just dislike the assumption that a poorly behaved class means a rubbish teacher - it doesn't.