Teach your children these basic firearms safety rules:
Always assume that a gun is loaded, even after you have personally unloaded it.
Never, ever, ever point a firearm at another person. NEVER POINT A FIREARM IN THE DIRECTION OF ANYTHING EXCEPT A PROPER TARGET AT A RANGE OR WHILE HUNTING.
Never handle a firearm unnecessarily.
Never accept a firearm from another person unless they have shown it to be unloaded in front of you. Never assume.
Always verify the unloaded condition of a firearm.
Never throw, drop, or otherwise mishandle a firearm.
When encountering a strange gun (say lying in the street), do not pick it up. Contact an adult (preferably a law enforcement officer) as soon as possible. When possible, keep other children away from the gun. Do not make any assumptions about a "found" weapon.
When firing at a range, always keep the gun pointed down range, towards the targets.
A firearm is not a toy. Do not treat it like one.
Do not show off firearms to friends and schoolmates. And, do not tell friends and schoolmates that there are firearms in the house. Do not take a firearm from its place without a parent present.
Always use proper ear and eye protection when at the range.
A firearm is not a status symbol, or indicator of strength. Do not use it as one.
Whenever you are in doubt about a firearm, do not touch it. Get an adult to check it for you.
Remember, it is our right to keep and bear arms, but it is also our responsibility to do so safely. It only takes one little mistake to cause a big accident.
Let them know that firearms are capable of bodily injury, destruction and possibly death if misused. Do not "soft-soap" the truth. Apply the same principles as Driver's Education courses in the schools do.
Start your children off right by showing them the ropes about guns. This includes showing them the proper procedures for unloading, verifying and handling a firearm. Where available, a certified instructor should be used to teach proper shooting and safety technique.
Make sure to show your children how to clean and care for a firearm. A dirty, or abused gun is more dangerous than any other.
Encourage your children to learn these safety rules, and to follow them. One method that helps is to take them to the range (once they are old enough to handle a firearm) and let them shoot. Another method is to use airguns in early training and safety education. This will not only further strengthen the other lessons, but will also serve to remove the mystique that has been put up around firearms. It is this mystique that leads to most firearms accidents today.
Remember, nothing is as good as education, and open, honest discussion.
When there are many children visiting, secure your firearms in a proper lock-box, safe, or unreachable location that you can monitor. Keep all spare ammo separate from the guns.
If your child is alone in the house regularly, consider getting a small safe or lockbox to keep your firearms in when you are not there.
Be sure to follow all of the rules you set for your children. If you violate any of them, the child will feel uncomfortable in following your example.