There is one instance in which it is actually less than desirable to be 'centered'.  That is, when it comes to your photographs. (Actually this applies to all forms of visual art.) It is generally accepted that a composition is more pleasing when the subject is slightly off-sides rather than dead center.  For a couple hundred years now this has been referred to as the rule of thirds. 

If you imagine a nine-patch quilt square superimposed over your image, you want to try to position your camera so that the subject is roughly near one of the four points on the center square. This can be done during focusing or later in editing. There is a trick to doing it in camera however because most point and shoot cameras tend to hunt for a center object to focus upon.  

First things first, you need to track down the way your camera is currently set to focus.  Does your camera have face recognition? Does it have flashing boxes in the viewfinder letting you know what it is selecting as focal points?  These are important things to know because whatever is outside the little flashing box(es) may well not be in focus, particularly if you are in Aperture or Portrait modes. 

Next, get your subject into a focus box and press the shutter half way down.  This will lock your focus and exposure.  Many people don't realize that your camera needs a half second there to do that. If you routinely press the shutter button completely immediately without that pause you aren't allowing your camera to focus properly. 

So, you have your subject locked in.  Now, move your camera slightly one way or another to frame the scene and then depress your shutter button the rest of the way. If this takes too much time you can always play around with cropping in your photo editing program.  They all have that. I would suggest making a copy of your image first and then try cropping it different ways for comparison. 

This one is pretty obvious. 

In this shot the tunnel is centered, but you can see that the girls themselves are aligned at the 1/3 and 2/3 marks.  This makes for a more symmetrical composition than Aidan's but still works. 

When she was solo, however, I moved Tess slightly left.

The Rule of Thirds doesn't apply only to portraits.  Some gorgeous examples of landscape and still shots here.

Weekend Challenge: learn to identify your camera's focus indicator and practice holding the shutter halfway down and recomposing your shot.  Alternatively, choose some of your older photos and play around with cropping.  (remember, always edit COPIES, never originals – cardinal rule of editing)