1. Never leave your registration and insurance in the vehicle. This can be useful in a few situations: someone steals your car and gets stopped, sometimes they can talk themselves out because try have valid registration and insurance, so unless the car is reported stolen they are just "borrowing" it from a friend. If the info isn't in there then they raise suspicion even if you don't know it's gone yet. Or, someone breaks into your car now they have your name, address, and other info.
2. Keep your cell phone charged, or an emergency replacement (some are available for under $20 and plug into any phone for a small boost) If you are lost or break down one call can make all the difference
3. Lock the doors when in the car. This can keep strangers out and children in.
4. Always use a seatbelt. You want your kids to wear one when they are older so teach them now.
5. Keep an emergency kit. I hope you never need to use it.
6. Learn how to change a tire. Teach children old enough to drive, or with friends old enough to drive, how to change one as well.