Be specific. If possible, use one short sentence to clearly state the reason for displaying the dialog box and the actions that can dismiss it.
Use complete sentences for messages where possible.
Use vocabulary that users understand. For example, use “The file could not be saved because the media card is full” instead of “Error writing file to disk.”
Use positive language where possible and avoid blaming the user. Never write messages that blame users for errors or unexpected conditions. Instead, focus on the actions that users can take to resolve the issue.
Use the second person (you, your) to refer to users.
Use sentence case capitalization.
Avoid using exclamation points (!) in messages.
Avoid using an ellipsis (…) in messages unless you are indicating progress (for example, “Please wait…”).