Open or tilted windows are invitation enough. Modern security fittings make prying them open harder; high-quality locks to DIN standards and at least security class 2 turn door-opening into a problem. A supplementary crossbar acts as both a physical and psychological deterrent.
Don’t display valuables to a burglar: don’t store jewelry and electronics in plain sight; instead use a built-in wall safe. An alarm system that notifies your smartphone and visibly apparent security measures raise the threshold for entry. Networked neighbors and timers for lights create a presence even when you’re away.
Exterior lighting with motion sensors and well-planned hedges and fences reduce hiding places. And very important: never post obvious vacation absences on social media and never hide keys under the doormat.