If you’re looking to create a timeless sense of purpose and to shape the overall mission of your life, then you should use principles. Establishing a set of principles creates a compass to which you can refer whenever something is in doubt or you need to take a stand or evaluate any particular opportunity, behavior, or situation.
"Who cares if the first draft is good? It doesn’t need to be good, it just needs to be, so you can revise it. You don’t need an idea to start a story. You just need a sentence"
- George Saunders
(good advice in general)
How do you get from starting small to doing something great? By making successive versions. Great things are almost always made in successive versions. You start with something small and evolve it, and the final version is both cleverer and more ambitious than anything you could have planned.