Writing tragic death scenes...

Think about it like real life. Who would you cry over? Someone you know and love, or someone you just met? The reader has to really care about the character.

Give the character potential, perhaps getting married in a couple days.
give them dreams and goals.
Build them into your favorite person in the world,
the tie the noose.

Happy_the_hipster read my mind.

In order for a heart to be broken, you need to have something to break; a connection needs to be made between reader and character. So, step one? Develop that character and give him/her a personality. Rather than writing the death scene right away, give your readers time to develop a relationship with your character. Think about it: If you heard that somebody died on the news, you would feel bad. The sympathy would be there. But unless you knew that person, you would not cry over it.

Step two: Don't rush. Let the death scene unfold naturally, voicing your protagonist's thoughts as the character breathes his/her last. If you find that your writing isn't up to par--if it doesn't capture the sorrow--wait until you’re sad before you write it. When your tears start flowing, vent. Write your thoughts on the page--but don't think about what you write. Just capture the feeling and the way the words come together. Then, after you grab a tissue and dry your eyes, visualize the death scene and let it unfold.