HI Mel,
I founded a bike advocacy group, non profit, about 5 years ago. Although our focus is different, some of what I/we went through may be beneficial for you to consider.
You've got some great advice above, but mine comes from a different angle, which is more the personal level of involvement. The following is about building a community organization, versus a personal organization
-Build a team right from the start. You will put a lot into this, and burn out is inevitable.
-Delegate. Micro management will accelerate your burnout, and piss people off.
-Be open minded to other versions of the vision. Keep the principle of what you are doing above what you personally think you should happen.
-If someone has an idea, they should have the freedom to fly with it. You never know what great things may come from someone else that you never thought of.
Your vision may morph as other get involved, but that should be OK as long as the PRINCIPLE is maintained. When the organization is about what you want and what you think should happen, it becomes nothing without you. Building a team is about finding others that are as passionate as you are, so that when you do burn out, there are others waiting in the wings to step in and take over ( this is where I failed).
good luck
2015 Liv Intrigue 2
Pro Mongoose Titanium Singlespeed
2012 Trek Madone 4.6 Compact SRAM