I would just like to ad some simple common sence (I hope it's not needed)
When diving with new divers, have them go down the anchor line, so they have a reference line to follow.
Do help them remember to bring a surface marking. Also so you know where they are.
If they AND you decide that they can swim away from the boat, and you the pick up the anchor, follow the surface marking, but in som 50 / 100 meters away. so you don't run them over. (After some practice you might be able to follow the bubbles, but only in calm weather).
Decide on a time, when they should be back in the boat, so you know when to call for help if they don't show up.
Try to think of a way for you to contact them, so you could call them to the surface in case of problems. (try to pull on the surface marking
Don't have the engine running when picking up divers (or any other persons from the water)
This was my advice for now
Safe diving and driving