Avoid overusing “please” or “sorry.” The message can be personable and inviting through tone and word choice.
Don’t blame the user. State what happened in a way that doesn’t make it their fault.
Sound like a human. Use conversational language. Contractions are okay. Keep it simple.
Check the language on existing error messages for reference.
Form Field Label Standards
Email
Use “Email.” Do not use “Email Address.” When referencing the formatting of an email address:
you@domain.com or your_friend@domain.com
Phone
Use “Phone” (not “Phone Number”). Use “Mobile Phone” if the situation calls specifically for mobile, such as text notifications.
Addresses
Use “Address” for the first line and “Address 2 (optional)” for the second line. Follow ZIP Code guidelines above.
Payments
“Security Code” (not “CVV”)
“PIN” (not “PIN Number”)