I've been installing fire alarms and security systems for 18 years now and am NBFAA (Level II) and NICET (Level I) certified.

A good starting point is contacting every opening (windows and doors), then either motion detectors or glassbreak detectors. I prefer motions, but in some cases they are not viable (large pets that roam the house, areas that are not heated/cooled, etc.)

Money comes into play a lot in security systems. I've done everything from 1 door contact on a system all the way up to DOD and UL systems where every square inch of the building is covered. On a DOD or UL certificated systems, you must cover EVERYTHING. As you can guess, those systems are by no means cheap, but they are the best you can put together.

Wireless is coming into it's own nowadays as a very good option if you don't want to have to run wires everywhere. Some brands are better than others. The wireless equipment I've had good experience with would be CADDX/ITI and Ademco/First Alert. Other manufacturers make wireless, but we don't use much else besides those.

The basic system consists of a control panel, one or more keypads, battery, AC transformer, and door contacts. If you go wireless you have to get a wireless receiver of the same brand as your control panel, and wireless transmitters. Wireless costs more than hardwired, but it saves a lot on time/mess when installing the system.

You can get by without a motion in every single room by placing them where they cover large, high-traffic areas like living rooms, hallways, etc. The motions are usually set up where they are off when you are home ("STAY" mode) and on when you are gone ("AWAY" mode).

Anything else you need to know, just ask.