Ask a friend to help out with reading the script with the actors. You might see extras potential in some passersby. You've spent six weeks preparing for this shoot, and now everything's going smoothly. But now it's lunchtime. Now you must spend a dollar or two.
Shooting is intense, and frustrations are easier to field when stomachs are full.
Buy a carton of water, and set up some coffee for everyone. So long as your crew knows your aims, you can delegate tasks to your technical crew. It never does. The actors will catch on to this experimentation and will improvise on their part, too. During editing, you'll be glad you got different shot styles for the same scene.