As an apartment dweller, there are a lot of steps you can take to improve security. Protecting yourself and your possessions should be one of your primary concerns. I'm going to give you a few of suggestions here to help make your apartment a little safer, a little more secure.
First, let's talk a little about doors. When you moved in, the manager should have changed the lock on the front door. Sure, the previous tenants turned in their keys, but keys can be copied. So if the locks weren't changed, who knows how many people could be walking around out there with a key to your apartment! The frame for the door should be in good condition and solid. You should have, at minimum, your standard door lock and a dead bolt. The dead bolt throw should extend into the frame at least 1" and the strike plate should be secured with 3" screws, long enough to anchor it to the stud.
Finally, if you have a peephole, use it!Sliding Doors. You should have an adjustable door brace or "charlie bar" to keep anyone from sliding it open. Even a broomstick cut to length will work really well. Sliding doors are notoriously easy to jimmy open. One other thing to consider here is, you should use an anti-lift device. These doors can simply be lifted up and pushed out. After all, that's how they were installed! You can install an anti-lift pin assembly, which is secured to the sliding half and the pin seats in the frame of stationary half. A second option is to install sheet metal screws in the top rail every several inches with the screws only partially screwed in. The heads should be exposed enough to let the door slide, but at the same time, prevent the door from being lifted.
On the subject of windows, everything that applied to sliding doors, applies here for sliding windows.
In addition, there are clamps which attach to the window rail which will allow you to open the window just a little for ventilation. You should place them to allow the window to open no more than 6". Another device you may consider is a glass breakage alarm. If the window or door is bumped or the glass broken, it sounds a really annoying alarm, hopefully alerting your neighbors!With the windows and doors out of the way, I'd like to add a few more suggestions to consider. First, cameras and alarms. Let's suppose the bad guys do manage to break in even with all the precautions we've taken. With a well placed hidden camera you might get some nice footage which would be an immense help to the police. You can get these cameras with everything (camera, DVR, etc) built into everyday objects, such as clocks, radios and fans.
I mentioned alarms. Maybe you don't want to get a monitored system for your apartment. You can, however, get an alarm system which will call you if the alarm is tripped. These usually come with the option of sounding an alarm (make sure your neighbors know!) or a silent mode.
For the times you're not home, you should have your lights on a timer. You could even put a TV or radio on a timer. If it looks like you're home, chances are really in your favor the bad guys are going to pass you up. One more thing before we move outdoors. Document your belongings (video, photos or written records) including make, model and serial numbers. After you've done this, get renters insurance! It's cheap!
Outside, if you have a balcony or patio, you might consider a motion activated light. It's not a bad idea even if you're not on the first floor. Make sure all of the outdoor lighting works and that shrubs or other plants don't provide hiding places in front of windows or doors. If lighting needs to be replaced or plants, trees, etc . need to be trimmed, let management know and follow up. Lastly, get to know your neighbors and look out for one another. Know who belongs and who doesn't. This can go a long way toward making your apartment complex a safer place to live.
There are a lot of suggestions here and I don't mean to imply you need all of them! You can pick and chose what you think will work for you and your budget. In large part, your safety and security is dependent on you being proactive. Be aware and stay safe!