If we want to build our credibility with other people, we have to first of all be credible to ourselves. That means selling ourselves on our products or our services first. If you believe you are selling a good product, or offering a valuable service, you won’t have much difficulty selling that product or service to other people. Your body language (open, confident) and your tone of voice (positive, enthusiastic, pleasant) will tell them that you believe in what you are selling.
The first impression goes a long way to establishing your authority. You want a clean vehicle; polished shoes; trimmed, clean fingernails; clean, groomed hair; no heavy scent or body odour; and preferably only one bag. Women must have their briefcase and purse under control to prevent a cluttered look. (If you can, scale back to just a briefcase.)
As well, be aware of body movements. Don’t fiddle with your hair, tug at or adjust your clothing, play with your beard or moustache, or otherwise fidget. Fidgeting detracts from your credibility and your confidence.
If you have a demonstration, this can add to your credibility. However, ask permission first, and know exactly what you are doing. A demonstration that goes wrong sells nobody.
If you have testimonials, you can have several written up and ready to pass out, or you can have the names of people willing to be called. Please, make sure you ask their permission first and get the correct contact information for them. Keep any testimonials or contacts up-to-date.
Matthew Coppola 
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