Assault rifles: Civilians are already prohibited from buying machine guns. Chopping down the length of the barrel of a rifle decreases its accuracy, but makes the gun lighter. Add a high capacity magazine to rapidly fire bullets, and you have an assault rifle. Outlaw high capacity magazines, and the would be terrorist could do better with a regular rifle.
School safety: The army has an "officer of the day" program, in which one officer, on a rotating basis, is in charge of the store. Implement this with schools and large buildings, so that there will always be someone who knows what to do in emergencies.
Gun ownership: Ordinary people should be allowed to own ordinary guns.