We took a quick look earlier at the Trust Formula:     T = [C + R + I ] / S     with T for trust , C for credibility, R for reliability, I for intimacy, S for self-orientation. C, R, I and S are the key factors determining trust, and they all at least partly result from your own behaviors. Now, let’s focus on credibility a bit.

Credibility comes from your perceived domain expertise. This perceived expertise is the result of your actual expertise, be it technical, functional, industrial, regional, etc. filtered by how you convey it. People will judge both with whatever they have at their disposal. On the rational side, they will want to know if you are telling the truth. Do they trust the message? To do so, they may check your references, the accuracy and currency of your “facts”, and the authority of your sources. On the irrational side, they will want to know if you are telling all the truth. Do they trust the messenger? They will be influenced by your attitude and presence – how you look, talk about what you know, listen to people, act and react, how you qualify what you know vs. don’t. To address suspicions of incompleteness, you must spend time prior to your meetings anticipating your clients’ needs. During the meeting you have everything to gain in asking good questions that will dress a panorama of what they need and what you know, through different lenses,and you may risk a  few unexpected perspectives. Don’t go too far, though. I have noticed that when you know so much that you know where they will fail and discuss these points, they will believe you’re wrong and hence not credible if they don’t see it. Better stick with the basics at the beginning. 

To be more credible, know your stuff and show it simply

1. Do your homework. Know what you are talking about
2. Surround yourself with as or more credible individuals
3. Support your assertions with facts and their sources

To be more credible, tell the truth, all the truth, only the truth

1. Say what you see, hear, assume, feel, know, think
2. Qualify what you say (fact, your thought, etc.). Say you “don’t know (but can check)” if you don’t
3. Don’t make up or alter facts, exaggerate, downplay, sugar coat (but stage as needed to be heard)

To be more credible, be present:

1. Be there physically: Dress the part. Maintain contact. Don’t check your phone, the game on TV, etc.
2. Be there mentally: Listen. Ask good questions – questions that make them react then pause and think
3. Emotionally: Tune in. Play the part. Don’t put yourself in the front unless you really belong there

In any interaction, the recipient of your message will always apply the ultimate filters to whatever they see, hear, etc. through their own beliefs, biases, fears, hopes. This influence materializes in three ways.
First, what makes you credible for a particular message to a particular audience in a particular context may hinder your credibility for a different message, audience or context. Think coaching an executive in his corner office vs. teaching him how to surf,  or conveying bad news to a Chinese Boardroom vs. great news to a French Boardroom. There is not one best way to dress, talk, or handle yourself. Yet, two kinds of people tend to really be credible: the ones who tune in, and the ones who absolutely disregard this advice. Without being disingenuous and “losing yourself”, you may adopt words and ways your clients use. At Applied Materials, we would always use engineering terms like “calibrate”. At Paris transport Authority, I would use safety shoes and carry a helmet most of the time. On the contrary, you may command attention by ignoring their customs. This is how star programmers wear long hair. It  says “$@#^ you, I can… now let’s speak about your problem”.  Take your pick. I tend to tune in, use their words, dress their way, and add just a little pinch of “not from here” to put people off-guard just a bit and get them to check me.
Second, the more you deal with executives, the more you deal with people with a long experience of interacting with people who want  or have to sell and advise them. These executives carry with them a long list of disappointments and negative experiences with past advisers or sales people. You may unknowingly be the victim of some of these biases and fears. There is obviously no perfect answer to that one, but I have noticed that building rapport first, being clear on what I know vs. don’t, then spending time on questions seems to have worked for me best across many industries and countries.
Finally, even if you do everything right, someone could disparage you behind your back. It works in politics: many campaigns have been won after undermining the opposite candidate’s credibility – think Ronald Reagan saying “I will NOT use my opponent’s youth and inexperience against him” Do you even remember the other guy? It works in sales. Do not “pull the trigger first” if you want long-lasting relationships with your clients. Do not disparage your competitors. Your clients might (rightfully?) fear that you could burn them in turn one day. Instead, just frame each player’s strengths, weaknesses and interests. Then show how “your competitors may be a great fit for others, and you are a great fit for your client“. At the same time, this will show how some “might be inclined to say certain things”, and put you above the pack. I had reasonable success in diffusing credibility attacks that way.