Make sure the Google Cloud Platform account you are using has credit to create new projects.

1. Navigate to Google Cloud Console.
2. Click the icon and click the New Project button.
3. Enter the name of project and click the Create button.
4. Enable Cloud Vision API for the newly created Project.
5. Create Service Account for the newly created project.
6. Enter the Service Account name and click the Create button. Enter other details (optional) and click the Done button. The service accounts for the project are displayed.
7. Click the icon and select the Create Key button.
8. Select Key type and click the Create button.

A private key is saved to your computer and displays project_id, private_key_id, private_key, client_id, etc.