In my years of teaching I have found these tips to be really useful.
Say thank you after a command not please, It's far more forceful and makes it much harder not to comply.
Ignore the behaviour you don't want to see (within reason) and praise the behaviour you do.
Word instructions in a positive way. Instead of saying, "don't run," say "show me sensible walking."
Keep instructions short and simple. Instead of saying. "Okay first I want you to tidy up, then put your English books in the middle of your tables and then go sit in your Maths places," say, "tidy up, books in middle, maths places, dojos/merits for the quickest table, GO!
Don't fall into argument traps and use the language of choice too.
Typically this is what happens.
"Callum stop talking and get on with your work."
"I wasn't talking!"
"Oh yes you were, I saw you!!"
"NO I wasn't!!!"
"ARE YOU ARGUING WITH ME??!!!"
Instead.
"Callum, if continue talking you will be choosing (sanction), now get on with your work."
"But I wasn't talking."
"I'm not arguing with you, I'm simply telling you what is going to happen, either choose to get on with your work quietly or choose (sanction), now make the right choice, thank you."
Hope it helps.