The author of the article discusses seven "worst practices" when using Redis, a popular in-memory data store. The first practice is not setting a password on the Redis instance, which makes it vulnerable to unauthorized access. Another worst practice is using the KEYS command, which can be slow and clog the server as the number of keys increases. Numbered databases are also criticized for being isolated but not well-supported throughout the ecosystem. Hashes with many fields and values can cause performance issues, similar to lists with a large number of elements. Redis connections should remain open across multiple commands, rather than opening and closing them per command. Creating hot keys that access the same data repeatedly can lead to performance issues and make the cluster less efficient. Finally, using Redis as a primary database requires additional features such as high availability and durability, which need to be configured properly. The author encourages readers to avoid these worst practices and follow best practices for optimal performance and security.