You can be a trusted institution or a trusted individual.
A few weeks ago, I set out to buy some imprinted items. I probably looked at a dozen t-shirt options online before I picked CustomInk. Why did I pick them?
They weren't the cheapest (but it's actually very hard to compare). I picked them because the site is clean and professional. I liked that they're not weasels (they quote actual prices and actual ship dates) and they have non-trivial, easy to use software that makes it easy to upload graphics and build a shirt.
Taken together, they earned my trust. There were plenty of sites with lousy typefaces and come-on pricing and bait and switch and clever Google ads, but none of this works on me. What works is someone walking the walk while they talk a good game.
Interestingly, I bought the hats from a totally different business. Roberts Specialty couldn't be less formal or carefully built. It's clearly a family run business, and their lack of spin and hustle hit exactly the right tone. When you want to order, you send an email to Tony Bennett (you gotta love the fact that his name is Tony Bennett) and he sends an email back. How old fashioned. How trustworthy.
One reason that so many hard sell businesses fail is that they are neither. They aren't (or don't appear to be) trustworthy institutions, nor are they trustworthy humans. So we move on. You do 95% of it right, then use cheesy fonts or lie a bit or try too hard and boom, that's it.