Bridge Over Troubled Water

I've spent the last weeks thinking about the gameplay, and only about that. I can't make up my mind on some important design decisions. In my head I just play an average turn trying to imagine the results given a certain set of rules. So basically I'm sitting on a chair with my giant scrapbook and start write, or I just do something else hoping that inspiration will hit me like a lightning. It happened in the past, but this time inspiration is taking too long to appear, so I'm a bit depressed.
The whole issue is how to treat lines of communications and reinforcements. The decisions I take now would heavily affect the gameplay and the amount of sheer fun of the players, so I can't leave it to a later time, I must write it down and have very clear ideas. In this respect I'm following a very ordered kind of development, the one you can find in every manual.