Get close before you give the direction. Eye contact, a hand on the shoulder, help them focus and listen, they're the direction itself. You're signaling to their brain that something important is coming. Calling across the room works for adults; however, it often doesn't work for children. I taught my teacher prep students that they only time you should scream across a room is if a child is in danger, like trying to climb up a bookcase…. oh yes, saw that many times.
Give one direction at a time. If the task has multiple steps, walk through them one at a time and wait for each to be completed. This isn't about lowering expectations.
Tell them what to do, not just what to STOP doing. "Stop running" gives the brain a prohibition but no target. "Walk, please" gives it something to move toward. Ormrod's work on behavioral learning consistently shows that replacement behaviors are easier to adopt than suppressed ones.
Offer a short transition window. "In two minutes, we're going to clean up" is easier to respond to than "clean up right now." It respects that they are in the middle of something their brain considers important, and it gives them time to shift gears. This is a key part of any classroom with multiple children to coordinate.
Name the reason when you can.Explain to them, "We need to leave by 8 so you're not late for school" lands differently than "I said so." Children who understand the why are more likely to cooperate and more likely to internalize the behavior over time.