Priorities and empowerment
Can't agree more strongly how vital it is that the workload is prioritised and then the people handling the work are trusted to get on with it without being micromanaged.
Every time a new task appears I have a conversation along the lines of "Here's what is on my worklist, I'm currently doing the thing at the top. Where does this new task fit in to the list?" That way the only thing they can complain about is how inaccurate the estimate is for how long the vaguely specified task will / did take.