Organizing Thoughts

I've reached a point in one of my projects where I can't seem to put pen to paper (figuratively, since I write everything on a computer). Not for lack of an idea. Conversely, it's too big of an idea.

I am one to normally sit down and write with a very general concept and almost no planning outside of a central plot point. Even then, I don't always stick to the plan. 

Since I have never written any story which exceeds 10,000 words, I am really struggling to organize my ideas into a cohesive narrative. There are episodes which revolve around the central idea, but all of them seem to be interchangeable with no structured order to them.

Any one of the choices I could make would get me started writing, but I have to also contend with the possibility that making a wrong choice might make me disenchanted with the writing and stop with the project altogether.

I have had at least one idea go down the tubes due to poor execution. This idea is too special, too valuable to ruin it. I need to find a way to power though the struggles and growing pains.

I probably need to just write at the end of the day. I need to come to terms with the idea that whole blocks of text, subplots, and characters might need to be balled up and tossed into the trash before I get it right.