A system is not software.
It is a documented way of doing something that works every time — without you.
Three things. That is all a system is:
1. The steps written down in order
2. Who is responsible for each step
3. What done looks like
A checklist on paper qualifies. Start there.
My first business system was handwritten. Not an app. Not a CRM. A piece of paper — and that piece of paper is what let us bring on a second person without quality dropping.
The system does not have to be perfect to work. It just has to exist.