1. Create a new user group. [Setup] -> [Groups], [Actions] -> [New]
2. Add yourself to the new group. Example: "Personal" [Setup] -> [Groups] -> [Personal] -> [Users]
3. Create a new role. Example "Personal" [Setup] -> [Roles], [Actions] -> [New]
4. Add your group (Personal) to the role (Personal). [Setup] -> [Roles] -> [Groups]
5. Go to the Personal document type and click on ACLs [Setup] -> [Roles] -> [Personal] -> [ACLs]
6. Create a new ACL and choose your role (Personal) and grant it all the permissions you need/want. [Actions] -> [New ACL]
Upload a document using the "Personal" document type and check as another user or a test user to make sure the setup worked.