The Data Model is the core logic of your business, and Hubspot is more powerful when you are using your own data model.
Your Data Model can be accessed in the Data Management menu in the main Hubspot navigation.
The key objects to focus on at first will be the Contacts, Companies, Products, Deals, and Tickets, If it's relevant to your business, you can also enable Appointments, Courses, Listings, or Services from the Object Library, or you can also define Custom Objects if your account is on an Enterprise tier.
First, download all of the properties in your account by going to Settings -> Data Management -> Properties, and clicking on "Export all properties" in the top right corner of your screen. This includes all of the current properties that are configured in your account.
You will do this collaboratively with your team, so it's best to download the XLSX version and place it on a shared folder that everybody can access. Google drive works best since it will be easy to collaborate with others in real time via your browser.
Each Object will have their properties organized by Group Name. The first step is to create a general group which includes information for any and all records within your CRM and then create property groups that are unique for each of the records according to your customer segments, decision-making units, and operations.
Hubspot already has many useful properties enabled by default. As a best practice, create a new group called "General Information" together with the other groups, and move Hubspot's default properties into the appropriate ones. This way, you will avoid duplicating properties that Hubspot has already created.