If your serious about someone actually taking action during a break in, a professional system like ADT is hard to beat
It however, comes at a price
For a DIY option, consider SmartThings, Scout, or Simplysafe
Camera's, signs, or warnings about guns or dogs are laughable at best
It's all about non altercation, good insurance, and recordings for the inevitable lawsuit
I've come home to a smashed window/door, and missing valubles more then once in my life
We all slept in the living room with a bat that night...
Signs are not laughable. Robbers don't want to get caught. The threat of getting caught makes one house less desirable than another.
Why would a lawsuit be inevitable?
My Simplisafe system is as good or better than any ADT system I know of. The times I've accidentally set it off, they were calling me within 20 seconds to see if everything was ok.
Don't bring a bat to a gunfight.