First, you should aim to understand the project's goals and target audience. What are the main objectives of the website, and who are the users? You mention two user types, so you should consider their needs, motivations, and pain points. This information can inform the design decisions you make later on.
Next, you can create a site map or user flow diagram that outlines the different pages and how users navigate between them. This can help you identify the key pages and functionality that need to be prioritized.
Once you have a good understanding of the project requirements and user needs, you can start working on the actual design. You mentioned layout, styles, and user interactions, which are all important aspects to consider. You can also include guidelines for typography, imagery, and icons, as well as any animations or microinteractions that enhance the user experience.
Another important consideration is accessibility. You should ensure that the design is inclusive and accessible to users with disabilities, such as those who use screen readers or have visual impairments.
Finally, you can include any technical considerations, such as browser compatibility, responsive design, and performance optimization.
As for a process for UI design, there are many different methodologies out there, such as Design Thinking, Agile, and Lean UX. You may want to research these and see if any resonate with you and your team's workflow. Ultimately, the process should be flexible and adaptable to the project's needs and constraints.
I hope this helps give you a starting point for your UI/UX design document!
To know more about UI UX, It's recommended to join UI UX Design Course today