So You Start Out With This Really Great Title Which Is Basically Your Thesis But Then You Start Writing And All Of A Sudden You Realize That Your Title Has Nothing To Do With What You Just Wrote
"If you are like most students writing a short paper, you will stare at the computer screen for a while until you come up with a title. Then you will pick your way through your topic, offering an extremely broad introduction (see Glittering Generalities, below). You might also type in a few long quotations that you like. After writing fluff for a page or two, you will eventually hit on a fairly good idea. You will pursue it for a paragraph or two, perhaps throwing in another quotation (Short Research Papers, Avoid Distractions, Stay On Topic)."
I am so guilty of this. Not the Glittering Generalities part but the getting off topic part. Almost every paper I have ever gotten back has said something about my lack of focus. I do exactly what is described in that passage: I come up with a great title (which I make my thesis), I start writing a whole bunch of fluff, then I touch on a great idea (which has really nothing to do with my current thesis) and I write about it for a few paragraphs and then I conclude my paper and never go back to fix my title or thesis to match my new brilliant idea.
Talk about ridiculous. Sometimes I just wish I had that brilliant idea in the first place so I would not feel like I wasted three pages on a thesis that was completely worthless. I have found that one of the best solutions for my problem (though it does not work for everyone) is to use freewriting as a form of prewriting. Some people use charts, (I usually make lists) but when I freewrite, I get a whole bunch of ideas out all at once (and some really great sentences too). I then choose my brilliant idea from that freewrite and continue from there. Brilliant ideas do not always jump out at me from my prewriting lists. Sometimes it is better to just start writing informally to get an idea for a formal paper.