I've followed some of his suggestions. The most important to me - at least - in view of the apparent increase in "home invasions" here - is that we NEVER answer the front door directly. Our house is two level and the front entrance is at the mid point between levels and I had a bay window installed on the left side of the front door. We ALWAYS answer the doorbell at the window and, if it's someone we know, it's easy to let them in. Otherwise, all conversation takes place through the window to my wife's left.
Salesmen (and anyone "casing" the house) get discouraged soon - particularly when told "Speak up - I can't hear you over the dogs barking".
Being 1/2 story up and on the left side of the person at the door - in addition to the brick wall - there's pretty good protection form anyone who might intend to shoot us with our having the good cover. Besides, I think the obvious "welcoming committee" impresses most visitors at the door.
"Little" sis (brindle) on the right weighs only 199# and big bro (fawn) is 202#.