I have learned that using deeper and brighter pigments is best and really helps bring out the person's features better. I try to avoid bronzer and iridescent powder that has any silver hues in it because it will not blend well into the skin and it can make the skin look ashy. Another trick I've learned is using MAC's Arena eyeshadow as a highlighter instead of Shroom or Mylar, which will look too white on darker skin tones.
For someone who is older, it's best to use more creamy, dewy foundations. Be sure to go light handed on the loose powder when setting. See my previous post (Conquering Deep Lines On The Face) about filling in lines and wrinkles and follow the steps on stippling the foundation in. When skin looks dewy and glows, it makes a person look younger and also reduces the appearance of fine lines and wrinkles!