When it comes to handling and processing large datasets in a desktop application, there are several best practices to follow. First, it is important to consider the hardware and software requirements of the application to ensure it can handle large datasets efficiently. Next, optimizing data storage and retrieval methods can help improve performance. This can be achieved through techniques like indexing, compression, and caching. Additionally, utilizing parallel processing and distributed computing can further enhance the speed and efficiency of data handling. Proper error handling, data validation, and security measures should also be implemented to ensure the integrity and privacy of the data. Overall, a combination of these best practices can help desktop applications effectively handle and process large datasets.