Create a Base Security Role with the Absolute Minimum Privileges

In order to configure a base security role to give a user the absolute minimal security privileges to access Dynamics CRM 2013.

1. In the Settings and then Administration, click the New button to create a new Security Role.
   
2. In the Details tab, enter a name in the Role Name field.  I gave it the name, Base Security Role.
   
3. In the Core Records tabs, select User/Create, Read, and Write on User Entity UI Settings.  (Note, the image has been truncated to fit.)
   
4. In the Business Management tab, select Organization/Read on Business Unit, Organization, and Security Role.  Select Business Unit/Read on User.  Select User/Read on User Settings.
   
5. In the Customization tab, select Organization/Read on System Form, View, and Web Resource.
   

Summarize Base Security Role Permissions:

Tab	Entity	Create	Read	Write
Core Records	User Entity UI Settings	User	User	User
Business Management	Business Unit		Organization
Business Management	Organization		Organization
Business Management	Security Role		Organization
Business Management	User		Business Unit
Business Management	User Settings		User
Customization	System Form		Organization