Okay, let's still say that you're not a consultant and that you don't ever plan to be. Let's say instead that you are seeking employment. Having once worked at an employment agency, I have written the following advice to you from my former perspective at an employment agency:
Some of this material is NOT going to be politically correct, so just forget about political correctness and lose any ethnic or cultural sensitivities you may have. In this modern day's business world, you do need to adhere to certain social conventions, whether they match your own or not. If your personal conventions depart too far from commonly expected norms, be assured that nobody will care about that as you exit through the door without having gotten a job for yourself.
Assuming that your resume attracts a headhunter's attention, you are likely to be asked to come in for a visit. When you come, learn to have controlled yourself. Dress nicely, dress properly and present yourself well.
For example, do not laugh, at least not too much.
Late one afternoon, when everyone in this particular agency's office was very tired from a long and hard day, this fellow came in for a talk. Every couple of sentences or so, he'd start laughing. It was a nervous laugh, and when it was repeated over and over again, it became very, very, very annoying. I guess he was trying to create a light-hearted atmosphere, but when he left, mention was made about laughing hyenas.
Learn to speak well. You are not Caspar Milquetoast who speaks like in a super-suppressed-quiet-gee-I-hope-nobody-can-hear-me kind of whisper so speak up! On the other hand, you are also not Luciano Pavarotti or Paul Robeson so don't try to make your voice sound BIGGER than it is. You'll sound like you're choking on a scarf. Just speak up nicely in your normal voice and make yourself easily heard.
If you have a non-English accent, that's okay unless it interferes with people's ability to understand you. One man whose accent was rather difficult for my ear was very offended by the suggestion that he needed to improve his spoken English language skills. "I was the best English student in Cairo!" was just not enough to solve the problem that I simply could not understand what he was trying to say to me.
Don't fuss with yourself. Women, don't twirl your hair around and around. Men, leave your necktie alone. Don't fidget.
Just before you meet with the agency person or the potential employer, realize in advance that you will be expected to shake hands.
Don't be Mr./Ms. Limp wrist, but also don't try to impress anyone with the physical strength of your grip. Even former heavyweight champion George Foreman has hand trouble these days and trying to do that, even to him, can cause him pain. Bad idea, right?? You have no idea about that issue regarding whoever is in front of you, so don't try it.
Also, when you know that you will soon be shaking hands, sneak in a moment to dry the palm of your hand against a handkerchief in your pocket. You do not want clammy to happen!
Forget about the garlic for a while. Before you come, shower and brush your teeth. Does it sound strange to hear that advice? Let me say a few things about that.
Some people have biological traits that they cannot control. It is no fault of their own, but some people will break a sweat with only a little bit of physical exertion. I myself am one such person and it can be a problem, but it is a problem I have had to recognize and deal with. If you are also some such person, you have to do the same.
If you have dental problems, that can lead to odorous breath that no amount of toothpaste or mouthwash can alleviate. If this is true for you, get the necessary dental care.
Do not wear (women) heavy perfume or (men) heavy aftershave. Some people are allergic to those things. It might be the person who will be judging you.
How is your mood? If you feel like five pounds of used food, don't let it show. You are literally in the middle of "show time" when you meet someone from the agency or the prospective employer and you need to look alert, aware and generally in a good, upbeat mood. Under no circumstances allow yourself the luxury of sarcasm or cynicism. Those two things do not go over well, so consciously guard yourself from using them.
Yes, there's more to come.