Any time you invest effort in a character to make the audience identify with them and like them, and then you kill them off, you're most likely going to evoke a strong emotion (sadness, anger, fear). If not, then you've got a major problem with your script.
The trick is to underplay it, not overplay your hand. If you overplay it, you get "Love Story" bathos (Ryan O'Neal and Ali McGraw). Today's audiences, I think, are savvy to being manipulated. Trust the story and the depth of your characterizations to evoke the emotion you're seeking.
As for "techniques," music is always a good way to heighten emotion, but again, be careful of being maudlin and don't rely on a background score to do what you should have done with your writing.
There's a fantastic scene at the end of "The Deer Hunter." Michael, good to his word, brings Nic home to America and, after Nic's funeral, the cast gathers at a local bar for breakfast and sings "God Bless America." It's simple and enormously powerful. And it never fails to bring a tear to my eye. The lesson is: just have the characters be real and true to themselves and do what real people do in the face of death, and you will succeed.
Cheers!
-Charles