Personally I picked a few scenes that really interested me & grabbed my attention, then I started filling in the areas inbetween.
- Write it as you see fit
- Get trusted people (you can post a link on the forum, the CoG community are trustworthy :D) to test it
- Repeat steps 1 and 2 until you are happy
- Finished! This can also work with other parts of the story- if you don’t want to spoil the story for us, get trusted friends/family to test it for you. But remember, a few people liking something makes it good , but a lot of people liking something makes it great