Oh, for Full Duplex

How to use a walkie on set. I cannot over stress how important it is to wait for the tones to go across the network (after pressing the talk button) to speak.

Note that the sound department almost never uses walkie talkies (typically called "radios" by professionals). This is primarily because they're listening all the time and can't be interrupted. Also, they're intimately involved with set and the sound of a walkie would destroy a take.
The few times when I've needed a cue from a walkie I've asked that a PA with a radio stand near me and relay the cue to me. (On other kinds of big shows I used to mix the communications were crazy-time complicated with multiple channels of hard-wired and wireless communications. That's not the case here.)
Press the PTT button. Take a breath. Then talk. Why? Because then the words "Don't move the truck" become "Move the truck." I have seen that happen way too often to count. Truck gets moved. "Why are you moving the truck?!" someone squeals. But it comes out as "Are you moving the truck?!"
The response is "yes". But they don't wait and the response becomes "... phtht".
So then an AD runs, yelling at the truck driver, avoiding the use of technology in order to communicate: "Why are you moving the truck??!!!"
"Because that's. What you told me. To do. On the radio."