Give Specific, Clear, Concise Instructions
This is especially important for students who have behavioral issues, and students who are struggling to follow instructions.
Don't Assume the Instruction is Understood
Give instructions, even for minimal tasks, so you can say, "I gave a clear instruction about ____." This will combat the student excuse of, "I didn't know."
Be Wary of the Fast Talker
If you find yourself justifying your instruction to the same student (student who argues with the rationale) - go back to the initial instruction, and add on, "the next step is to say ok, and do it right away." After follow the initial instruction - then you will justify your decision (which usually doesn't matter anymore).
One at a Time!
If a student isn't following instructions, do not pile more on. Stay with the initial instruction.
Humor