In business it's easy to tell who's the veteran and who's the new trainee. Besides the fact they wear nicer suits, veterans have an aura that says, "Trust me, I know what I'm doing." What's the secret behind this aura? Two things: Poise and Credibility.
1) Understand yourself in mind, body, and spirit. If you know yourself inside and out then you'll know whether the problem is with you or with the client. If you know you've done your work properly to the best of your ability then the problem is with your client. But remember, in business the client is always right.
2) You are what you wear and what you wear should again say, "Trust me, I know what I'm doing." What's the rule? Make sure your clothes are fit, not tight nor loose, use proper color coordination, keep your clothes clean, and lastly remember this line, "these clothes don't make me look good; I make these clothes look good." You are the center-piece of your attire, not the clothes.
3) Walk with confidence because how you walk shows how you go through your journeys in life. Show your confidence with a straight body and keep your head high. Just imagine you're wearing an invisible crown whenever you walk and you'll be treated like royalty.
4) Credibility should start from within, so set your mind with the right perspective: I am confident, positive, and glad to be who I am. Love yourself and everything else will follow.
In the end poise is how you carry yourself and credibility starts with believing yourself. It takes time and practice, but what the mind believes, the body follows.