Ever think to put your landline phone's ringer on mute so that prowlers don't hear an unanswered ring while you're gone? And if you use an answering machine (yes, some people still do), set the volume to very low.
Before bringing an extension cord outside for use, make sure it says it's suitable for outdoor appliances.
Don't leave notes on your door saying "back in a minute" or anything like that, no matter whom you're expecting.
Do you have a smoke detector on every floor? Did you know that dirt buildup can interfere with their sensors?
Upgrade your smoke alarms to be interlinked so that if the one in the basement goes off, the one on the third floor will too.
Thinking of recharging a non-rechargeable battery? Just buy new batteries. Otherwise, it might explode.
Discard oily rags by hanging them outdoors for drying, then toss inside a metal can with a cover. An oily rag near a non-flaming heat source can still combust.
Don't panic about perishable food if there's a power outage; a freezer will preserve food for two whole days.
You just got hit with a big snowfall, your car's hidden in the garage, and you don't need to leave your house for a few days. You may still want to go out there and shovel so that potential intruders know you're home.
Place security signs on your property, such as decals for a security company (whether you use one or not) on windows, or a "Beware of Dog" sign, even if you only have a timid cat.
Have thorny shrubs planted near windows to deter intruders.
Before leaving for a trip, inform a trustworthy neighbor-and discreetly; don't yell it across driveways.
Please, abstain from posting pictures of your vacation on social media until you get back home.