The most challenging part of business planning

Rich

In my experience, really in-depth and substantive market research is the most elusive and difficult part of building a business plan.
What are your thoughts about the most challenging part of writing a business plan?
Maybe we can get some dialogue going here to get some of these planning roadblocks out in the open so others who`ve overcome them can share tricks of the trade for you to do the same.
Rich

Rich

interplanet,
soon we`re releasing 10 Steps to Grow Your Business as a follow-on to 10 Steps to Open for Business, and we`re including in Step 1 the important use of online surveys just like the ones you mention as a way to get a sense of your business` current status.
i guess i hadn`t thought about using free online surveys before you start up.
ahhh, the power of thousands sharing their ideas...
rich
 

boywithadrum

Hey guys, I wanted to pipe in here.  I am fairly new to Startup Nation and I just wanted to thank you for your hard work and for sharing your knowledge to better your fellow entrepeneur`s experiences.
One of the hardest things about writing my business plan is that my huge over time plans are vast and interconnected.  They are too involved to accurately write a plan for those big future ideas right now, but I need a plan done asap.  I am trying to write a simple plan covering only the first stages of my company`s development, but knowing where to draw those lines is difficult.
I don`t want to over commit right off the bat but I want to command enough attention so an overview is necessary I feel.  I don`t want to grossly under or overestimate my potential so that investors can realize in the plan that it lays a foundation for growth, expansion and bigger and better things to come
I know I am being vague here but the line is fine and it`s blurry here.  Chime in if you can help with financials especially for the first time plan. 
Thanks   BoyWithADrum. . . . .