Setting the right emotional tone is a critical first step for anyone in the "trust business." If you want people to entrust you with their general health, teeth, personal finances, legal issues, business security or whatever, you have to write content that projects a mix of reassurance, encouragement, and empathy. For instance, have you ever scared yourself to death looking up Internet articles on this or that health symptom? You probably uncovered a blizzard of articles that took a severe, alarmist, worst-case scenario attitude to the subject. Just as a doctor understands the value of a proper bedside manner, you must emphasize that you understand the client's problem, you sympathize with his situation, and you can apply your skill and expertise to help ease that discomfort.
Consider the intellectual "mood music" you're including in your content. Of course you want to assure the world that you're intelligent, well-educated, and knowledgable in your field. But as I pointed out in a previous post, overly-technical terminology can put up obstacles instead of getting readers on your side. I've written for attorneys who wanted me to refer readers to specific court decisions -- citation numbers and all. Unless their clients are aspiring lawyers, that strategy is more likely to drive ordinary people away than to draw them in. On the other end of the scale, if you make an obvious attempt to "dumb down" your content, you're potentially insulting your readers. Keep it simple, keep it clear, and let the knowledge shine through.
Last but not least, think about whether your content reflects honorably on your chosen profession. For example, are you making inappropriate promises? There's a huge range of commitment between "we will," "we can," and "we may" in a piece of marketing content. Depending on the rules of your profession, you may be highly limited in what you're allowed to offer or how you're allowed to offer it. On the other hand, if your content has no backbone at all, your reader may wonder why you even bothered stating anything. Make sure you know the rules of the game, whatever those may be for your field, and stay inside the lines. But commit to the bottom line: doing everything in your power to help those who need your professional expertise.
Choose the right "suit of clothes" for your professional marketing content, and you'll make it a lot easier for people to trust you, understand you, and take you seriously. If you need a professional writer's expertise to help you make that happen, you know who to contact!