Conversation is an often-lost art. I don't mean in the conventional sense of a general social debilitation that many might argue, particularly in reference to generations younger than theirs. Instead, I mean the sense of feeling stymied when interacting with someone you don't know, who is from a different background, whether differentiated by power, money, fame, work, education, or social niche.
We all frequently default in our private lives to interacting with those who are like us, which is sad. You miss opportunities to learn and grow by such insulation. However, in business there may be no option to stay comfortable. If you're an entrepreneur, you will at some point talk to people who are more successful, perhaps potential investors. In sales (and who in business isn't in sales?), you will speak to anyone and everyone who might listen.
To do so, you need to surmount the barrier of discomfort, and not by adopting an overly familiar tone that can border on condescension. (I once spoke to an entrepreneur who referred to Steve Jobs as "Steve," although he had never worked for the man or, so far as I could tell, ever met him.)
Forget the affectations. You can talk to anyone if you follow a few principles. These have helped me in work and life comfortably speak with CEOs of the world's largest companies, politicians, famous performers, regular working stiffs, and even prisoners.
Anxiety, worry, excitement, and other agitating feelings can knot you up, affect your thinking, and leave you almost physically incapable of speech. There are many relaxation techniques, including meditation, progressive tightening and releasing of muscles, and working areas like your jaw and neck. Before a scheduled meeting or telephone call, find a place where you can ease some of the physical tension.
Be polite and respectful
Everyone wants respect. Treat people as you would want them to act toward you. Don't immediately presume to use someone's first name, for example. Start with Mr. or Ms., as a little formality goes a long way. If the other person uses your first name, feel free to use his or hers in return. But show that you value the person's existence and don't take his or her individuality or importance for granted. Remember basic manners and that all individuals within their own sphere are important to themselves and those they know and love.
Remember that no one is special
The flip side of the previous point is that no one--I mean absolutely no one--deserves awe or giggling fandom. There are people who have done great things, made significant amounts of money, achieved fame, broken new intellectual ground, or amassed power. Respect them and recognize what they have done, but remember that they, too, are just people, who have problems and weaknesses, who make blundering errors, and who will die. Some might change the world, perhaps, but more likely at most you face another Ozymandias, as in the poem by Shelley: "Look on my Works, ye Mighty, and despair!" They are not better than you, so respect yourself as well.
Talk by listening
A conversation is a two-way street. The standard advice is to always listen more than you talk. That's not bad, but the problem with any ironclad rule is that the proper application depends on the situation. There will be times when someone wants to hear from you. Just remember, even then, that you help people open up, and keep yourself from potential trouble, by letting someone else talk more than you.
Take interest in the other person
People are stuck on and in themselves. This is a human condition. Even many who would pose as enlightened gurus, or masters of the world, still have human foibles. They get angry, sad, and generally have all the burden of egos that we do. Even if people don't like to talk about themselves, for whatever reason, they perk up when speaking of things that they find of interest or importance. Let someone talk about his or her passions and you will be amazed at how the person opens up, and how you can take interest in what is happening before you, not in some image of who you think someone is.
Remember what you have in common
Are you dumbstruck before your friends? No, of course not, because you share too much experience and interest. To talk with anyone, find the points of commonality, which means looking into your life and experiences to see where you can make a connection to the person and what the person is saying. That will, in turn, help the person connect to you.
Remember why you're talking to the person
When feeling particularly stymied, remember any specific reason you have to speak with a given person. No matter what his or her station in life, it's lower than the immediate need to satisfy your goal. Use your intent to add a bigger context.
Then forget the goal
The danger of a goal in a conversation is that you can become manipulative if you direct everything to achieve your end. What you want will come out of an honest and real experience of communication. Let your goal keep you from being mired in awkwardness, but remember that its fulfillment will be a result of truly connecting with someone. Let the means justify the ends.