Well, when I come up with titles, one thing that I think of is brevity. Personally, I shy away from lengthier titles - I feel that it should be short and catchy. My first series, Biophilia, was very easy to name, because biophilia is something that's essential to the story, and it's also an interesting word on its own that doesn't get thrown around too often and may grab attention. For my other series, Bright Light, I only came up with the title later on, and its based on something to do with the main characters. I feel that it's better than anything else that might have to do with the actual story, so I made that call and stuck with it.
However, the only rule I followed with these two titles is that I wanted them to sound good to me. I chose them because I was happy with them and felt that they would represent the series nicely. So, my only advice would be to think really hard until you come up with something that satisfies you. Like, once when I had no idea how to name a comic I was doing, I ended up naming it Whatever This Is Called - and it works! It fits with the spirit of the story and the characters, and I don't need to come up with another one.
So, ruminate on what lies at the core of your story and what words you feel would represent it best to your readers, but don't go overboard. It's not that a long title is bad per se, but less quite often is more.
(On a jokier note, "Death! Death!!" would be a great title for something. I would click on that the moment I saw it. But I kid.)