Of the people that take responsibility for their "self defense" (ie. not freeloaders on society), the most common tool is a firearm.  Today, the sales of handguns far out number long guns.  
Of the responsible citizens, that I know, they will have a hand gun on their person from the time they put on clothing in the morning until bedtime.  A gun that is attached to you and under your direct control is certainly not going to be accessible to children or "dangerous" persons.  I do agree that guns that are not in use should be secured suitable to the environment where they reside.  A safe is certainly one common method.