Doing What Works: Forward in Solution-Focused Change: Dan Pink on motivation and engagement

10 Tips to make your writing more solution-focused

Make it useful by asking in advance what the other person's expectations are from your text.
Make it simple: make your words, sentences and structure no more complicated than strictly necessary.
Match the use of language of the other person.
Respond adequately to comments and questions.
Formulate positively: whenever possible, use positive and specific language.
Activate the other person: ask good questions.
Motivate your choices and decisions in a compact, clear and positive way.
Check whether you have understood the other person well and whether your text is useful for him or her.
Invite the other person to offer feedback, suggestions and corrections.
When, in a proposal, you offer more than or something different from what the client has asked for, it often works well to mention that part as a separate module in your text so that it will be much easier for the client to choose or ignore that part.

More about this here.