There are fifty videos available on the internet which demonstrate that every lock, also the safety locks (and lockers), in seconds are opened by 'experts'. You only can make it difficult and time consuming, so that candidate burglars prefer to drop out.

Install a decent lock, and use it: close doors and windows when you are out or sleeping.
For ventilation use vents instead of open windows. Also a small toilet window (up to 15 x 25 cm) is large enough for an intruder! (So probably place a grating.)
Open windows, you can protect with a rim lock (door chain, hook). So they cannot (easily) open further.

windorgelUse appropriate cylinders. Protruding specimens can be clamped with pliers and be broken. Instead there may be a firm, round, sloping rose(tte) around. Or a cover plate which includes the latch.
The upper, sloping and retractable lap of a lock can be operated with the handle: the latch bolt. The deadbolt only with the key. In a latch lever turns the key the deadbolt open, and as you progress it also runs the latch lock. You then actually have, as on the door of a toilet, no latch or rotary knob needed on the outside. That is a safer option.
The bolt must be long enough (2 cm). But also the strike plate in the edge profile around the door should be firmly.
Make openings (letterbox, cat flap) so that from there the key is not accessible. Even not with a wire. Let no keys in the lock. Or fix them by connecting them to the latch so that they neither rotated nor can be fished out with wire.
 'Hide' no keys under the doormat or planter.
Hang no address label on your key.

Make windows and doors closing tight, so that no one can pry between.
Windows that can be opened by lifting the crank can be easily opened from the outside through a hole borer. See if you can prevent this by a pen through a hole in the crank. Or place a side slot or laches.
With a hole above and below the lock intruders manage also to turn a key from the outside. So do not leave keys. (Or secure them.)

A cellar hole obviously gets a solid iron grid, with a taut chain and a lock.
Let the house look used and inhabited, even if you are (a long time) absent. (No full mailbox!)
Don’t sign absences with notes on the door, phone messages or messages on social networking sites.
Hang no visible address label on your suitcase, everyone at the airport, at the hotel...can see that your address has been abandoned for a long time.
Show no valuable items (mobile phones, notebook..).
Do not put all valuables (money, jewelery, bank cards) together on one spot.
Don’t put a ladder (or other burglars material) ready against the wall.
Close also stables and shed. And note that the hinges are not at the outside on doors and windows.

Screen not everything with dense and high fence, which makes social control by the neighbors impossible.
Outdoor light with a good adjustable (light and motion) sensor is also useful when you come yourself home after dark. And if it does not respond to all cats. Make sure cable and lamp are not (easily) accessible (for sabotage).

If you go to sleep you can additionally secure the closed door with a bolt lock (or even a bar) on the inside. A door spy glass (magnifying sight glass) may also be useful.
You can also hang a wind chime (tinkling tubes or bamboo) on the door. Which then makes noise when the door opens.
Or better yet, hang the wind chime on the door handle, so it thunders on the floor when the latch goes down. You can also just set a box with keys or marbles on it. Also provides sufficient noise as it falls. But if it is not stable, is bumped or accidentally fells off, you have to search and pick up everything again. So prefer a wind chime.
Or keep a dog.