Another way to do so is to put one of these on your door ......Only the first time.
When I was living in an apartment complex, I got home from work about 0700 one morning. Threw my jacket on the couch and headed for the fridge.
Knock at the door (which was not unusual at that time in my life ). I opened the door to two Jehovah's Witnesses, not exactly what I was expecting. Their eyes got a little buggy, and they simply said "sorry to bother you sir", and left.
Didn't think anything of it. Went to the head and caught a glimpse of myself in the mirror....still wearing a shoulder rig with a Smith 6904 and two spare mags.