Your car insurance premium will automatically be lower when you install a security system in it. This is due to the fact that having security in your vehicle lowers its theft risk, and all insurance is based on risk. If your car insurance company knows that your car has a less chance of getting stolen, they know that they will be less likely to have to pay out.
If someone tries to break into your vehicle, a good, loud alarm system will alert you and any people nearby to the incident. Your alarm system, dependant on its ability, will have a range of sensors situated around the vehicle. Some of these systems activate when someone tries to open a door handle, or a window is broken. More advanced alarm systems even have motion sensors around the vehicle so that it will go off if someone even leans on your car! Luckily, you are able to choose the sound of your car alarm, so that you will be able to recognize and distinguish it from others.
It is good to have a clear, loud alarm system, but you have to also consider what will happen if there is no one within earshot or the thieves work very quickly. The security system INSIDE your car also has to be efficient. You can deter potential thieves with a good gear locking system. Unless they have a metal cutter, they will not be able to steal your vehicle with a gear lock in place! It is good, of course, to have backup security measures in your vehicle. An anti hijack system, which will cut your vehicle from operating if a hidden button is not pressed, will almost certainly stop the thieves. Some immobilizer systems will not allow your vehicle to start without the keys until a special key has been inserted into the anti hijack system.
In addition to all these abovementioned security systems, you can also install a tracker system on your vehicle. A tracker system will find your motor vehicle through satellites, no matter where it is in the world. So therefore, if your vehicle is stolen, it will be found and retrieved by your tracking company.
In addition to all these security measures, you can also put some tinting on your vehicle's windows. This way, potential thieves will find it more difficult to see inside. There are a lot of smash and grab attacks, where a thief will break your car window at a traffic light and steal the valuables in the passenger seat. With tinting, they will not be able to see what you have on the seat so that they can do this. It also helps with the theft of your car radio and such when you have parked your car. Ensure that you are always vigilant at stop streets, traffic lights and when parking your vehicle, as sometimes thieves prefer to attack whilst you are still in your vehicle!