In the last few years, we've turned to Jenna Lyons for insight on everything from career advice to how to cuff your button-down shirt. The creative director is a wealth of knowledge, and thanks to her most recent interview with Garance Doré, we now have a long list of etiquette dos and don'ts, from thank-you cards and interviews to elegance and how to have a conversation. This video is a serious must-watch. Also, Lyons shares the "most important" rule of etiquette. Click above to find out what it is, and shop J.Crew's latest arrivals to get the Lyons look.