Having been in the past a .... uhhh... "shady character" at times....
(I have since gone the straight and narrow for a LONG time)
Just the sign in your window will scare off MOST burglars.(most home invaders have no real skillz at overcoming a pro security system anyways)
But they only work if you turn them on. and actually cover ALL entrances to your house.
INCLUDING the 2nd or 3rd floor.(and basement entrances, old coal loading chutes, attic vents, etc....)
Want to test one, try to break in yourself.
---------Just remember if you can fit your head through, it can be entered by a determined thief.------------(and yes I have done this....

)
Most long term thieves I have met are quite limber.
Motion sensors are REALLY easy to get around/not set off.
But only when the potential thief can SEE it.
Mount any all video cameras and motion/thermal sensors :
1.) OUT OF REACH!
2.) out of direct sight.
It's best to use a housing for your security lights/cameras that are shatterproof, both on the housing and the lens used as well.
A motion sensor hooked to a light that was knocked out the night before(from a wrist rocket/pellet gun/thrown rock) does no better than a dead dog.
AUDIBLE alarms are good at scaring someone away, but can turn into a bad event(you want to meet the burglar while he is amped on adrenaline from the alarm going off??), SILENT ALARMS(IMO) are best. Let the cops/security company guys deal with the crack/meth/coke junkie in your garage/house/basement/attic.
And if nothing else.... ILLUMINATION is a thieves enemy.
Simple good illumination kept me(and the crew i ran with) from MANY a house back in my drug daze.....
And thinking a dog will protect your yard...... Sometimes, if the dog is trained... yes.
But a hungry dog will eat a good steak.
And the dog will never know what was stuffed in the steak either remove his ability to bark, or knock him out.
And I have seen both happen more than once to pits, rotty's, pincers... even pomeranians.
(the little ones are the hardest though, they don't eat much and tend to be pampered by the owners and less likely to take the food you offer/throw over the fence)
Another thought, thieves LIKE tall security fences, the neighbors can't see in your yard as well.
Chainlink is better IMO.
l8r