There are many resources online that can help someone become a virtual assistant. Here are some of them:
Virtual Assistant Mastery has many tutorials on how to become an excellent virtual assistant.
The Virtual Assistant Association offers a variety of resources for virtual assistants. They offer information on the latest trends in the industry, various certifications, and much more!
The VA Community also provides a great resource for VAs. They offer articles on topics such as how to be successful as a VA, how to handle difficult clients, and many others.