There's a joke about how Excel is the most popular tool in the world for writing fictional stories.
If you're preparing a revenue projection, for example, it's really easy to simply add a zero and work backwards from there to make all the other numbers work out.
When you're trying to raise money – an investment for your business or a donation for your cause – you'll need to have a story to tell your audience first about the impact they will have.
The story needs to be true. Or at least close enough to being true that your contributors are taking informed risks.
But if you're trying to initiate something new, start by crafting the most compelling story you can. If you get that correct, and others share your vision, the rest will fall into place.