Gino Wickman’s EOS is a favourite on my reading list.
In it, Gino posits that every business has these 6 processes:
HR - how you find, banish and/or nurture talent
Marketing - how you generate interest from your target audience
Sales - how you turn a prospect into a customer
Operations - how you actually deliver your service
Accounting - reconciling the business with its finances
Customer-retention process - how you keep customers and turn them into promoters
Each of these should be describable in a few bullet points. These ‘principles’ become particularly important as you grow, it’s an opportunity to distill what ‘works’ and not relearn it as you turnover staff. I call this document your ‘universal process’, everyone should be able to access it and everyone should be able to understand it.
From there, each department can go about how they do things in detail.
In an advisor capacity, I find this model a useful way of reviewing a business I am looking at i.e. are these processes functioning and understood.