How should your story end?
First of all, why are you asking me? I'm just some guy. I started this blog as a dude who enjoys writing, and since that was just a few days ago you shouldn't be taking anything I say as gospel. I appreciate the thought, but please do your research as well.
So let's talk about endings. How do you go from starting a story, from beginning the journey of a new and lovable character, to the denouement and the final page before all the back patting begins? To be honest, I've never had a dedicated process to finishing my story. Often I'll start an idea with the end goal in mind only to change it halfway through, and then again a bit later.
There's no science to it. As a creator, you must be willing to step up and ask the hard questions. If your story is worth the pages, then there must be a point to it all. Where does this quest your knight is on take him? Do the aliens win in the end? Was it all a dream?
Sometimes you have to write without knowing what comes next. I wrote most of my shorts with only the vaguest idea of where the end game took the reader. The novel was a little different, but as it turned into a trilogy there have been many deviations from the original plan. And I have embraced each one.
You have to be willing to roll with the punches. Sometimes that means your idea will twist and turn into something completely different from what you had to start. That's fine. Be willing to accept change. More often than not, change is good.
Here's your homework: Take any idea that you're working on and come up with two or three new endings. Go radical, don't just change the main character's hair color. And you know what? I think you'll be happier with some of the weird crap you divine.
If you're not, I'll be here. Let me know.