Chances are that if you're like me, you opened the box of your camera, put batteries in it and started taking pictures. That's not a bad thing if you got the same camera as you had before, but if it's a new brand or step-up model you'll want to take some time and read through your owners manual. If you've been into photography for awhile, doing this will help you navigate through different menu options & functions. Better to find your exposure compensation control now than in the field when you're shooting. Don't know how to set your flash to 2nd curtain sync? It's in the owners manual. Want to change your auto-focus point? Owners manual. Why are things flashing in your view finder? Check the manual! Use your manual as a reference guide and check it often, you may miss something if you only glance at it once.
The more you know about your camera and lenses the freer you'll be to concentrate on just getting the shot.
Everyone agrees that if you put your main focus in the centre of the photo your picture will be static. This is a common mistake that many amatuers make. Have a look at someones vacation photos and you'll see that everything is centered. The rule of thirds was not created to make better photos, it was discoved that better photos followed the rule. By dividing your photo in thirds horizontally and vertically and then placing your subject where those lines cross will allow you to add context or atmosphere to create a more dynamic shot.
This is also true for horizons. When composing your Picture shift the horizon away from the middle of the photo so that you don't have any lines bisecting your shot in half. By doing this you'll have to dedcide which features to emphasize more.