The Dalai Lama wrote that the best way to help others is to be selfish first: he called it "selfish wisdom."
The most obvious example is on an aeroplane.
When your hostess shows you how to use the oxygen mask, she will also advise that you put your mask on first, before you help a child with their mask. You before the child, not the child first (as most people would think).
It's obvious when you think about it - how can you help a child if you pass out? Then two of you would be harmed.