When we lived in town I did a few basic things like putting dowel rods in the windows/sliding glass door to make it more difficult for someone to get in, but we mostly rented in those days so we couldn’t make big changes. Someone tried to kick in the back door while I was home with the babies, but was apparently too weak to accomplish it. The door held alright, but I would have felt more comfortable if we had been able to install bars for the doors.
One thing that we are planning on doing is installing bright lights we can turn on outside for better visibility. We keep things pretty dim inside in the evenings so help save on electricity and to wind down. Right now the lack of lighting outdoors as both a deterrent and as a way to help us quickly identify who we are dealing with is something we need.
But if you can, try to get to know your neighbors a little, they will help look out for you. We lived in a variety of neighborhoods, some were “bad” but still had some good people, some were a mix of folks, and sometimes we lived on military installations (loved having seriously armed guards between my babies and the outside world). But in each situation having a few trusted neighbors really made a big difference in my peace of mind.