Show a character experience something that the audience has always wanted (true love, innocence, closeness with a parent), and then take that thing away.
Examples:
Have a baby be born and then kill one or both the parents
I have a softness for animals so they get me a lot.
Music or lack of plays a big empathy is a big part.Realism too, tears don't usually come out like a faucet. Usually people go through shock first and or try and hold back tears/contain their emotion. Higher cracking voices, stammering with words etc.