Creating a coding standards document

Question

I work in a control systems company, where the primary work is SCADA and PLC, along with other control systems stuff.

Software development is not really something the company does, apart from little bits here and there, until there was a decision to create an internal project management and appraisal system.

This project has been taken on by people who came here as software people originally and we are mostly junior.

The project started off small, so we only documented stuff like design, database stuff etc, but we never really agreed upon a coding format/conventions.

We started using StyleCop to make sure we had well documented code, but I feel we need an official document for coding conventions/practices so we can continue a good standard and if there is any more major development work in the future, whomever works on it has a good baseplate.

Therein lies the problem, I have no idea how to draft up a document for coding conventions and standards, all I can think of is examples of good vs bad practice (for example camel case when naming variables, avoiding Hungarian notation etc) we are all competent enough programmers (apparently) but we just don't have a charter for this kind of stuff.

To put a point on it, my question is: What are the key aspects and contents of a good coding standards document?