Amateurs want to center everything. The pros typically place the subject at one of the four intersecting points. This is called the rule of thirds, because you are dividing up the frame into three equal parts vertically and horizontally (sort of like a tic tac toe board). If your subject is a human, the eye is the most important part and so place one of their eyes in one of the four intersecting points.
Now, you may ask, which of the four points should you go for? The answer is in the very first tip I gave (direction & space). Scroll down and look for it :)