Securing your data
First and foremost the most important thing that you do with any of your apps is consider the security of the data itself. We can put a number of protections into the app that allow people to only see what we want them to see, but if they have access to the underlying data source then they could still get the data. This is extremely important to understand when using data sources such as SharePoint, where the underlying service provides its own user interface.
When using other data sources such as SQL, or Dataverse, it’s not as straight forward to be able to access the data directly, but that should be no reason why we shouldn’t still apply security to our data.