1. State Your Case With Case Studies
You can say "Trust me" until you're blue in the face, but nobody's going to do so until you've answered the obvious next question: "Why?" Even then, you can list all kinds of features, awards and accolades, but your prospective buyer may be more powerfully persuaded with a detailed look at how your products or services helped someone else with a similar need. This is where short case studies can do a world of good. Write up a few well-chosen paragraphs describing a past client's problem, the steps you took to solve it and the results they enjoyed as a result. Post it on your website and repeat as needed until you've got a whole "gallery" of success stories representing different industries and/or solutions.
2. Tell Them Through Testimonials
You don't always have to blow your own horn -- sometimes your satisfied clients are more than happy to sing your praises publicly. That's why you should get into the habit of asking for real, verifiable testimonials. If you've got people vouching for your quality by sharing their own delight with your work, pepper your online and off-line marketing content with it. The fact that this is one kind of content you don't have to spend time and effort composing is a nice fringe benefit.
3. Flash Your Credentials
Just as flashing a badge can get a plainclothes police officer past skeptical gatekeepers and other obstacles, displaying your professional and community credentials can help lower trust barriers. If you belong to local or national chapters of well-known associations, get permission to put their logos or banners up on your site and add them to your print marketing collateral.
4. Keep Sharing Your Expertise
The more you know about your field, and the more generously you share those insights with others who need them, the more deeply you'll reinforce your reputation as a trusted expert. Keep posting those interesting, useful blog articles. Make your voice heard on your social media channels of choice. Polish your website and print content until it shines with authority.
Trust has to be earned, and your marketing content can help you earn it. Contact me if you'd like some help taking your reputation to new heights!