Security Alarm works when the driver side is opened. All four doors should be connected to the alarm. The door sensor which triggers the alarm can be installed in the bonnet too. So if the bonnet is opened, the alarm will trigger.
Moreover, I would suggest to remove the cigarette lighter as some Jammers are powered from cigarette lighter socket.
I have came through so many incidents where cars have been stolen even with Trackers, Anti Theft Clutch bars, security systems, crook locks, steering lock etc. These morons can bypass all this security measures.
Rather than going for these technical security measures which can be easily bypassed we should go for something different.
First of all we should make it a habit not to leave the car unattended. In an unavoidable situation park the car in a place from where you can easily see it. Lock the car properly i-e Steering Lock, Crook Lock, Clutch bar etc. These things do not 100% security, but ur car will not look like an easy target to the thief. He would probably find some other car. Even if he still goes for ur car, the locks will make him panic a bit and the thief will require more time.
In home, try not to leave any space from where the thief could jump in. Normally some space is available above the main gate from where the thief can jump in. This passage should be blocked by Installing grills. Try to have atleast 02 locks on the main gate. It will add to the worries of the thief if he tries to break it.
CCTV camera can be installed in the garage or outside the home. You are not supposed to be infront of CCTV 24 Hrs, but atleast the thief will be a bit hesitant to target your home.
For cars like Mehran, Khyber, Cultus, Margalla etc you can remove the distributor cable of the car and take it with you. You can also remove some fuses which are responsible for ignition.
I would also advise a chor switch, not like the ordinary ones which can easily be tracked and bypassed. You can install a chor switch which are hard to track. You can install a switch with Fuel Pump, which will not provide fuel to the car to get it started. Another switch can be installed with Crank Shaft sensor, like in Vitz, Corolla etc.
Last but not least, every night before going to bed check the main gate locks and make sure the car is properly locked. Read Ayat al Kursi by looking at your car and door and only then go to sleep.