How to create a solid site structure.
Content Types
This is the main content structure for drupal.
Use content types when you want something to be editable and have a standalone page.
Use a naming convention for content types. I recommend sentence case.
Add a content type description so it's clear how it's used.
Fields
Fields are both a data structure and a form widget.
Actually the form widgets and display formatters are separate plugins, but the field type plugin defines the storage and values.
Field types
Text fields
There is formatted text and plain text.
Formatted text can have an editor and many enhancements that filter the text and render formatted html.
Take note of the different text field types before choosing one for your field. They are difficult to change later.
Reusing fields
Fields can be reused per entity type. That means you can use a field on different entities.
The field storage settings are fixed, like the number of items allowed.
Other things can be overridden, like the widget and display, and some field settings.
Name your fields based on the purpose so they can be reused.
Prefix fields with the bundle name when they need to be specific.
In the image below, items in Field Storage are shared, and the rest are specific to the instance.
Modules
https://www.drupalarchitect.info/module/content-model-documentation