Dead-Ball Foul Sequence/Mechanics

[The Roamin' Umpire]

Whistle first - it should be in your mouth already. The most important thing is to make sure play stops.

In theory, kill the clock is the next most important thing. In practice, I find it's easiest to grab my flag on the way by as my hands move up to stop the clock.

Also, for pre-snap fouls, get in the habit of tossing your flag to the side of the offending team. It tips your partners off so that they can start herding players in the correct direction while you're reporting the foul.