When taking photos of people, if timing/subject permits, think first about the background, then the subject. You want an uncluttered background that won’t distract from your subject.

Now that you’ve decided what background you want, position your subject to give them the best lighting (e.g. not sun in their face) while having the chosen background behind them. This will also tell you where to position yourself.  Make the subject take up at least 1/4 of the frame (e.g. how close do you need to stand or zoom to achieve this).  

Voila, a better picture than the usual snap shot that doesn’t take these things into account in designing the shot.