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 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. After that, you want a clean vehicle; polished shoes; trimmed, clean fingernails; clean, groomed hair; no heavy scent or body odour, and preferably only one bag.
As well, be aware of body movements. Again, 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 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 their correct contact information. Keep any testimonials or contacts up-to-date.