Windows would probably have to be the most popular choice for burglars to gain access to your home or business. In some older homes it can be as simple as slipping a bread and butter knife between two panes in your window, sliding your latch across then that’s it, your window is unlocked. This sort of thing can be easily prevented and can also be inexpensive as well as effective. You can use things as simple as a piece of dowel placed diagonally across the the top pane while sitting on the lower pane to prevent the window from sliding upwards when not in use (for vertically opening windows). Or the same thing except with the dowel resting horizontally preventing the pane from opening sideways (for horizontally opening windows).
You may even also choose to spend some money on window security. This sort of thing can include keyed lockable mechanisms that can lock your window at various heights or widths. Or, you may even want to spend even more money to get your windows hooked into an alarm system so that if it breaks or opens when set it will trigger an alarm. Even if you just put a sticker on your window advertising an alarm system this can be enough (even if you don’t have one!).
For window security though, one of the most important things is to remember to keep them locked or at least shut when they are not in use. Lots of homes get broken into because a bathroom or toilet window is routinely kept open or unlocked. These are favourite entry points for would-be burglars.
Overall though, when you are leaving your house or business make sure you check your windows are locked and shut. Once you get into the habit it will become routine and you won’t even have to think about it any more, it will be second nature! Just this simple checking could save you, your possessions and your family heartbreak/trouble that could have been easily avoided.