The standard tip is 15% of the total bill.
Business Etiquette Resources
Miss Manners’ Guide for the Turn-of-the-Millennium (Fireside; $20) by Judith Martin
The Etiquette Advantage in Business:Personal Skills for Professional Success(HarperResource; $35) by Peggy Post and Peter Post
Business Etiquette for Dummies(For Dummies; $21.99) by Sue Fox