One easy way to develop credibility with them is to create content to address their needs and share your expertise.
There are endless ways you can do this, but you want to be strategic in your efforts and have a content marketing plan in place. This includes outlining where and how you'll distribute your content (i.e. blog posts, articles, audios, videos, etc.)
I thought this was a great article to share a few key tools that will make your content marketing strategy more effective.