It's been my observation that people tend to express affection in a way that they most need it themselves.
Some people are very touch oriented, and express affection through touches and being close, others might give give praise and positive encouragement. There are, of course, a myriad of ways to express affection.
Observe how the people in your life express affection, if you can express it back in kind it might just make their day. 😄
@digitalfox
Agreed, certainly not a "catch-all" bit of advice, those are far shorter and infinitely more global - but something I've found useful in my general day-to-day actions. 😃