I've been thinking about this one, too.
If a weapon isn't on my person or I'm not at home, then it's locked up in a gun safe bolt to the floor. A couple of reasons for that, guns are valuable, of course, but more importantly, if someone breaks into my house and finds a loaded gun, now they're armed. I don't want to be shot with my own weapon.
If you can't afford a safe, then at least unload it and separate the weapon from the ammo. A lot of these shooters have been too young to even purchase ammunition...like that 16 year old in CA a couple of weeks ago.
I've even heard of some removing the barrel, slide, magazine, etc., and taking that with them, too.
As far as quick accessibility, there are a lot of fast unlocking devices out there that are reasonably secure. Not something that should be legislated, but I'm encouraging it.