Car seat safety cannot be over-done or over-stressed. If you're a parent who is interested in the welfare of their child - then this is important to you. Car seat safety is of the utmost importance to me - primarily because I'm a type-A control freak and this is one area where I ultimately have no control. I am a safe driver, however I don't know anything about the hundreds of cars around me on a daily basis - it only takes one person, doing something dumb to change my (and possibly my son's life) forever. Therefore, I arm myself with knowledge and a quality car seat, installed properly with him seated in it correctly (and never in a winter coat).
Recently there was this good article summarizing 9 basic car seat rules: 9 Life Saving Car Seat Rules You're Probably Ignoring. Christie Haskell does a good job pointing out a lot of "duh" things that perhaps parents are just unaware of (i.e. chest clip placement, reading your car seats manual, etc).
CarSeat.org (great reference site with forum!) has also released this super easy (and quick) document called Quick Check List for Safety Seat Misuse.
I highly recommend all parents occasionally check the tightness of LATCH straps or seatbelts and ensure child is as snug as possible in seat every time you put your child in - these small steps could save your child's life. Obviously my #1 tip is to thoroughly read your manual and get any questions you have answered to ensure that your seat is installed correctly - doesn't matter what brand of seat you have or how much you spent on it, if your car seat is installed correctly, it will perform correctly in the event of a crash.
For more on car seats see our previous post: Car Seat Safety