my mom didn't ever really wear makeup, but the one thing she taught me was that to always carry a bright-ish color of lipstick with me, because if I'm out and about without makeup on, and need to look good in a pinch, to pop on some lipstick, because it provides a focal point for your face and brightens you up right away. now i've amended that to have mascara & lipstick with me, just in case.
honestly, though, my mom really didn't need to wear makeup, she looked so much younger than she was, even right before she died, she looked 10 years younger than she actually was.
wait: she did always tell me to never go to bed without washing my face & applying a good night cream. that's proven invaluable to me, over the years.