First step, IMHO, is to sit down with your wife and talk this through. You'll need her buy in for anything to be effective.
Second step, again IMHO, is to work on hardening your perimeter. Your doors should be able to resist forced entry and many doors are a weak spot. Garages are also problem areas - some folks leave the remote controls in their unlocked vehicles. Don't be those folks.
Once you get the perimeter hardened, start walking your selves through the software side of things - actions on contact as it were. As 45gunner points out, one adult, two adults home gives you different options.
As a slight caveat, I'd probably spend a bit more time working on fire drills that home invasion plans. I've known several folks who have had major house fires, but no one who had their door kicked in. Just my opinion...