I need help with establishing a design guide.

Hi Everyone,

Two months back, as three college students, we decided on starting our own startup journey. We came up with a product idea that helps content marketers generate more leads and increase conversion rates.

Currently, we are about the finish our MVP and hoping to launch it in two weeks. But, there is an issue about our product that keeps bothering us:

All of us lack UI/UX skills. Although we are working hard to improve on them, we have hard time making design decisions as a team. Therefore, I'm thinking of making a style guide kind of documentation to settle on some basic design principles.

We are using Vue Material for our frontend. So, I'm planning on exporting material components to Sketch and making a newly updated mockup with some extra documentation on typography, colors, brand assets, etc.

Where should I start? What is the best solution for our case?

Any help is appreciated,
Thanks!