How can I prevent errors in VBA code?

Prevention is key. Use proper input validation to ensure that data entered by the user or from external sources is valid. Always check if objects exist before attempting to use them (e.g., `If obj Is Nothing Then ...`). Use appropriate data types for variables to avoid type mismatch errors. And, utilize `Application.ScreenUpdating = False` during lengthy operations to prevent screen flickering and improve performance. Finally, include comments in your code to make it easier to understand and debug.