A great outline to make your own can be found at http://www.secureav.com/briefing.pdf
FAA regulations require two specific tasks each time you take off with a passenger. The first is to brief your passengers on how the seat belts work. The second is to notify the passengers that seat belts must actually be fastened. That's in FAR 91.107(a)(1) and FAR 91.107(a)(2). Without doing these things you can't take off, land, or even move an aircraft on the surface.
But there are a lot more things going on for the passengers than that, such as whether they are going to be airsick. In fact, that may be topic number one for them, but out of embarrassment passengers are unlikely to bring it up. There are two ways to approach this delicate issue. The first is to be discreet; don't let a briefing be the power of suggestion that can actually make passengers sick once they get in the air. But place airsickness bags where they can easily be found. The second method is to be direct. Discuss airsickness and the location of the bags. Be aware that whichever method you use, airsickness does not get better once it starts. Suggest to the sick passenger that he or she look at the horizon, but don't prolong the flight unnecessarily. It may even be wise to make an early fuel stop, and don't be in a rush to get back in the air. Give the passenger an hour or two to recover.
The FAA's suggested passenger briefing checklist is based on the word safety, with each letter standing for items to be completed.
S for seat belts fastened for taxi, takeoff, landing; shoulder harnesses fastened for takeoff, landing; seat position adjusted and locked into place.A for air vents (location and operation); all environmental controls (discussed); action in case of any passenger discomfort.
F for fire extinguisher (location and operation).
E for exit doors (how to secure, how to open); emergency evacuation plan; emergency survival kit (location and contents); equipment (location and operation).
T for traffic (scanning, spotting, notifying pilot); talking (sterile-cockpit expectations).
Y for your questions? Speak up!
My husband flies with me often and he reads the checklist for me. I know he will not miss a thing on it, and it is a help. If you fly with someone you know and trust let them help you with tasks they can handle. He knows I have a habit of forgetting to set the transponder and is sure to remind me!
click here for another much more detailed look at the passenger brief