Do not reply
Check out and use the GMail security checklist
What if you receive messages asking for personal information?
Sign in to Gmail.
Open the message you'd like to report.
Click the down arrow next to 'Reply', at the top-right of the message pane.
Select 'Report Phishing'.
If you do not have a Gmail account, but would like to report a Gmail user who is sending phishing messages, fill out this form.
Report violations to the FTC
Report spam if you are outside of the US
File a complaint with the IC3 (Internet Crime Complaint Center)
Make yourself aware of Internet Trends and Schemes
What else do you recommend?