As I referee kids on a Sunday morning I incorporate my warm-up into my pitch inspection. Starting from a corner flag, I check it's okay, then jog at 60% to halfway line and then sprint the rest of the way. Heels up to the goal, walk around it checking it's okay and then knees up to the next corner flag. Same running along the side of the pitch and then side-step to the next goal and after checking it the same to the last corner flag and then a sprint to the halfway line where I do stretches.
Yep, that's the same approach I take. Seems to work OK and gets two jobs done at once!