I agree with Donna, there needs to be a balance. Keeping your wits about you is the most important safety criteria. Scaring everyone before you leave the dock, or giving them so much information they couldn't possibly remember it all, will just overwhelm the newbie and freeze them in their tracks. Makes seasickness more likely too, IMHO.
1. Life Jackets
2. No one leaves the cockpit without permission
3. MOB, point and yell, keep pointing.
4. Sailboats are supposed to heal.
5. Keep fingers and feet away from control lines.
6. Fully close the refrigerator door.
7. Laminated instructions on how to use the head are in cabinet over sink.
8. When in doubt, ask or sit still and await instructions. Don't guess.
Enjoy. The container in the fridge with the lime green juice is not just juice.
p.s. In a standard cut and paste email to all new guests, I send the marina address and list of stuff to bring. Proper shoes, windbreaker, sunscreen, etc, etc. They can check that off calmly before they arrive. I even list what they do not need to bring, as we have plenty of towels, sheets, pillows, etc.