When it comes to automating REST APIs in Python, there are several key concepts and libraries you should learn:

1. Requests Library: The requests library is essential for making HTTP requests to REST APIs. You'll need to understand how to use methods like GET, POST, PUT, and DELETE to interact with API endpoints.

2. JSON Handling: REST APIs often communicate using JSON (JavaScript Object Notation). Familiarize yourself with Python's json module to parse JSON responses and serialize data for requests.

3. Authentication: Learn how to handle authentication mechanisms such as API keys, OAuth, and token-based authentication to access protected resources.

4. Error Handling: Understand how to handle errors and exceptions that may occur when making API requests, and implement appropriate error handling strategies.

5. API Documentation: Study the API documentation thoroughly to understand the available endpoints, request parameters, response formats, and any rate limits or authentication requirements.

6. Endpoint Design: Learn how to construct valid endpoint URLs and incorporate query parameters, request headers, and request bodies as needed.

7. Testing and Validation: Implement testing practices to verify that your API requests and responses are working correctly. Tools like unittest or third-party libraries like pytest can be useful.