Don't Write a Business Plan. Create a Lean Canvas Instead. Lean Canvas is a 1-page business plan template created by Ash Maurya that helps you deconstruct your idea into its key assumptions.
Lean Canvas doesn't let you get away with vagueness, and the leanstack product set supports best practice startup behaviour especially when life gets busy.
I started to use it a long time ago and it is still the most effective and simple tool out there for your Lean Canvas creation
Pros:Easy to create and to share with all stackholders
Cons:Nothing so far