Possible Clues:

• "Don't forget ..."
• "But wait, there's more"
• ''And don't forget . . .''
• 'What's more . . .'
• 'Not to mention...'
• 'Furthermore . . .'
• It precedes an extra point
• "While we're on the subject ... "
• 'Not only that . . .'
• It may precede an extra point