Security is about creating layers of defense, with redundancy if possible.

Your windows and doors are the outermost layer. These should have good locks with reinforced hinges, locksets or window pins, and jambs, ideally with steel or at least solid wood/fiberglass cores. Burglar bars or gates are often on ground- and fire-escape-accessible windows and doors in high-crime areas, but pose significant safety risks in the event of an emergency, and may be prohibited in your building. Window security film provides good security without compromising safety and is more attractive than bars or gates.

After doors and windows comes curtains and lights. Deny a burglar the opportunity to see what valuables are available and chances are they will look elsewhere for a known pay-off. Leaving a radio on and lights on timers can be useful for inexperienced operators, but a pro burglar will usually stake out a neighborhood to watch for you to head off to work, rather than risking chance encounters with residents.

The next layer of defense would be an alarm system, and there are inexpensive wireless units ideal for temporary installation in apartments. Placing alarm stickers on your windows or doors, particularly for a high-end alarm system you might not really have, can be nearly as good a deterrent as an alarm itself.

The innermost layer is to protect valuables within your home. This includes using security cable locks on valuable appliances such as computers, tv's, etc., and a safe for important papers, cash, even laptop computers.

Conversely, if you are at risk for burglary a firearm is a liability. A burglar is not looking to enter your home while you are there. Unless you carry your firearm (with appropriate permits) make certain it is locked securely in a safe whenever you aren't present. The only thing worse than getting burglarized is putting a firearm in the hands of a criminal. The only thing worse than that is having that criminal use firearm against you if you catch him in the act.

Wireless cameras are only useful for documenting the theft, and even then, unless you go with a costly commercial system, rarely provide enough quality to positively identify the perpetrator. The only one I have personal experience with is the WiLife system from Logitech, now replaced with the Logitech Alert product line. This system requires a PC to collect the video and then uploads it automatically to Logitech servers, where you can view it remotely (from a PC or smartphone) or download it to provide evidence to the police if your PC is among the stolen property. I consider the PC to be a weak link, as they are prone to crashing or rebooting and hanging periodically. Using a dedicated PC for the camera system would be more reliable, but at that point the cost of a commercial system is within reach.