According to Pattie McNiel, Owner of First Impressions Training here are the top ten tips on Professional Business Etiquette:

1. When you walk into a room walk with purpose.  First impressions take about 5 seconds that doesn’t get you past the “how do you do?”  Dress professionally, not too much make-up or perfume/cologne, polished shoes, above all a nice smile on your face and a positive attitude.  People tend to gravitate towards others who portray a positive image. 
2. Business introductions are based upon hierarchy not gender.  Within your organization it is always Mr./Ms. Greater Authority I would like to introduce you to Mr./Ms. Lesser Authority.  When you have a guest, customer, or client from outside of your organization they take precedence over anyone within your organization.
3. During an introduction clasp hand firmly but not too firmly, make eye contact, and repeat the persons name right after meeting them.  This will help you remember their name.  Remember the sweetest sound to another person is the sound of their name.  To not make an introduction would be considered rude and cause embarrassment.
4. The key to networking is to make as many business contacts as possible for it make doing business much easier later.  Remember that once you sit down for dinner/lunch you will spend the next two hours with the same people at your table.  Try to pry yourself away from all the folks you typically mix and mingle with and reach out and get to know others.
5. When entering the room for an appetizer reception please do not make a fast break to the bar or food.  Mix and mingle with folks and then make your way to the buffet or bar.
6. Business dinner conversation should not include: religion, politics, diet, or sex.  So, what does that leave for proper conversation?  Always allow everyone equal talking time as it is never polite to monopolize the conversation.
7. During a business luncheon/dinner always follow the lead of the host.  When they state, “enjoy dinner” place your napkin in your lap. 
8. From a food safety standpoint always excuse yourself should you need to blow your nose.  Wash your hands thoroughly before returning to the table.
9. When you receive someone’s business card take a moment to look at it and make a comment if your intention is to possible do business in the future. 
10. When invited to a business lunch/dinner always take the time to write a hand written thank you note to show you appreciation.