First or Last?

I tend to approach my writing head-on: start with the first chapter and progress from there. I find this is the easiest way to bang out a story with a minimal amount of rewriting. Some people write whatever part of the story they're thinking of, and I suppose this works for some. I tend to find myself either contorting the earlier story to fit what's to come, or having to re-write large portions of the later text in order to match up with what came before.

For the past couple of months, I have been working on revising a novel I wrote a couple of years ago. I'd had the basic idea in my head, and wrote it quickly for NaNoWriMo. As such, it rambled, focusing on details that probably didn't matter, and glossing over more major events. As I have learned more about structure this past year, I've decided to rewrite the entire novel, applying as much structure to it as I can. This hasn't been easy, and work has been slow. One major problem I've had is that pesky first chapter. It doesn't feel right. I've written and re-written and revised and edited. I've torn it all down, and started from scratch. I've thought about it and fretted and I'm not sure I can think about it any more right now.

See, I want the first chapter to mean something to the rest of the book. Over the summer, I read "To Kill A Mockingbird" for the first time (yes, I am in my thirties and never managed to read the book; never had to read it for school, didn't know much about it, other than that some of my friends had to read it). I thought it slow at first, and even when the action picked up, and I was swept up in the story, the early chapters still felt superfluous. And then I got to the climax, and it blew me away. Scout talks about the final scene in the very first scene, and you don't realize how important that all is until the very end. That's what I want my opening chapter to do. 

I'm sure you could think of other examples, too. Books, TV shows or movies, where you see some unexplained action in the first scene that then ties into the climax. The Harry Potter series comes to mind, particularly "Goblet of Fire", when Harry sees Wormtail doing...something (Harry, and by proxy the reader, doesn't know what)...that later ties directly into the climax. 

Here's my problem, though: I haven't written the climax yet. I have an idea of what I want to happen, but I'm not sure exactly what will happen. So, as I write more of the story, I find that I keep being drawn back to that opening chapter, to try to shape it more and more, to make it something good. The more I do this, the more I think that maybe I should just hold off - write a sketch of what's to happen in that first chapter, then write the rest of the story. At the end, I can go back and fully write that first chapter. 

The only problem I can see with doing this is that if I want to let anyone read the story before it's finished, I don't have a first chapter to show them. Maybe I just need to outline more, and be more sure of the storyline before I start writing? Do all writers deal with this?

I guess I will just push through. Hopefully I figure this out soon. I've spent far too long on this one chapter.