Before starting to create a Flow, it's absolutely essential to design it first!
Why? Because Salesforce has made it super easy to create a Flow with point-and-click User Interface (UI).
But the issue with that is: You can have multiple lego blocks but if they don’t fit properly, the structure will eventually collapse.
A simple analogy: You wouldn't build a house without an actual blueprint, would you?
The same principle applies to Salesforce Flows!
It is necessary to think about:
▶ How the flow fits with the existing Org,
▶ Consider the scalability, governor limits, existing Flows that can be repurposed
▶ Using Flow-Sub Flow structure with reusable components
▶ Using Custom Metadata, custom labels and custom permissions to query a table that can be easily configured/enhanced
I can talk about few of those design patterns but one of the Salesforce champions, Rakesh Gupta have already covered in much detail here:
https://automationchampion.com/2021/10/19/salesforce-flow-design-patterns-from-fundamentals-to-mastery/
Read the article, design and build some flows with that knowledge!