Keeping your application secure can be achieved if we follow some basic rules of software security and implement them tightly in the application's development and production cycles:

• Never trust your user input: As developers of the application, we should make sure that we don't trust any user input. Everything that may come from the user side should be filtered appropriately before it is processed by the application for storage or any other kind of operation that may cause the provided input to be executed.
• Encrypt sensitive data: Any kind of sensitive data should have a strong encryption supporting its storage and retrieval. Having some amount of randomness in generating the encrypted version of the data can help a lot in making it difficult for attackers to get anything useful out of the data, even if they somehow got access to it.
• Properly secure the infrastructure: The infrastructure that is being used to run the application should be secured properly, with firewalls configured to restrict any kind of unauthorized access to the internal networks or nodes.
• Implement end-to-end encryption: Any communication that happens between two services should be end-to-end encrypted to avoid any man-in-the-middle attacks or sniffing of the information.
• Carefully implement bounds checks: If your application uses any kind of data structures, make sure that proper bounds-checking is in place so as to avoid vulnerabilities, such as Buffer overflow, which may allow malicious code to get executed.
• Restrict user permissions: No application should have a single user with all permissions given to them. The user permissions should be restricted so as to define the boundaries for a user to execute an operation. Following this kind of recommendation can help to restrict the amount of damage a breach may cause in case the credentials for a less privileged user are compromised.
• Keep the dependencies updated: The dependencies of an application should be kept updated so as to make sure that the dependencies are free of any known security vulnerability.

Following these kinds of guidelines can help a lot in improving the application security of your application and making sure that the application, as well as the data, is kept safe, which maintains user trust as well as data security.