Avoid Red Eye
Without going into all the technical (and physiological) reasons why people in our photos often get "red eye" when we use a flash, let's just look at how to avoid it. The main culprit is your camera's pop-up flash, which sits right above your lens and is an almost automatic recipe for red eye. The easy fix (the one the pros use anyway) is to either get that flash (ideally) off the camera and hold it a couple of feet away from the lens, or at the very least up much higher away from the lens, to reduce the chance for red eye. Another method is to bounce your flash off the ceiling, which is a great cure for red eye. Of course, all of these require you to have a separate external flash unit (and not just your camera's built-in pop-up flash). If you can't spring for an external flash, there are a few other popular strategies when you have no choice but to use your built-in pop-up flash: (1) turn on some room lights, if possible. It lets your subject's pupils contract, and that causes less red eye than shooting in complete darkness. (2) If your camera has a red-eye reduction mode (where it sends a preemptive flash, which causes your subject's pupils to quickly contract, before it fires the main flash), that sometimes reduces red eye. (3) Ask your subject to look slightly away from the lens and that will certainly help, plus (4) moving your camera closer to your subject can also help reduce the dreaded red eye.