How do you build street cred?
You need to let people know who you are. This pertains to building relationships with your customers, and since you are new with the business, you will build relationships with potential customers. Spend some time before launching your big business idea learning more about your industry and the people who spend money there.
You can always try selling other people’s products first – as an affiliate marketer and learn something new about the products you sell them. When you have enough knowledge and you are talking about the product online (such as on your blog), this will help build street credibility as the people who read it will feel you know what you are talking about.