When Chris Voss showed up at his hotel in Los Angeles recently before the official check-in time, the clerk informed him there would be an early check-in fee. Minutes later, he left the reception desk with the fee waived and a key to an upgraded room.

A former lead international kidnapping negotiator for the F.B.I., Mr. Voss is an expert in negotiation, and not just at hotels. He successfully negotiated the surrender of hostages during the 1993 Chase Manhattan bank robbery in Brooklyn. He has taught business negotiation at Harvard University and written about the art of persuasion in his book, “Never Split the Difference.” His new online MasterClass details the use of body language, speech patterns, empathy and bargaining — tactics he believes can be applied, from requesting a pay raise to landing travel perks and avoiding travel penalties.

The following interview, on Mr. Voss’s approach to managing travel hurdles, has been edited and condensed for clarity.

Are there basics to negotiation, like controlling your voice?

It’s great there are so many demanding travelers who raise their voices. It makes it easier for the rest of us. Start out friendly and playful. The idea is to convey “I like you and want you to enjoy this interaction.” It will come out in your voice and impact them positively before you finish your first sentence. The adage is: Never be mean to someone who can hurt you by doing nothing. If you’re good, they’ll be delighted to do for you whatever they can. A playful, enjoyable attitude gives you latitude.