Depending on your audience, some formats might be more effective than others. If this decision hasn't already been made for you by your employer, pick a format you think will be appropriate for your audience.  If your audience will be reading your document while carrying out a task, a technical manual or instruction sheet made up of bullet points and possibly diagrams may be most effective.  On the other hand, if you are hoping to inform professionals about new research in their field, an article or newsletter format might be best. Before you actually write your document, create an outline to organize and plan your content. This will not only make writing easier, it's also a good way to ensure that the information you have deemed most important will all be present, and that it will be organized in a way that will make sense to your audience. Outlines are also a good way of developing headings for the different sections in your document, which will be useful in helping readers identify the key pieces of information they are looking for. One of the most valuable things about audience analysis is that it allows you to select a writing voice that will be compelling and effective for reaching your audience. The right choice of words and sentence structure can make a big difference in getting your message across to your audience.  For example, if your audience is highly educated and/or well versed in the topic you are writing about, the use of highly specific and technical vocabulary may be acceptable or even helpful. If your audience is not well informed about your topic, such language should be avoided. Likewise, if your audience is likely to be reading your work while carrying out a specific task or in a work environment with many distractions, the use of short, simple sentences is advisable. If they'll be reading your work at home and giving it their undivided attention, varying sentence length and structure will make your writing more compelling and enjoyable. Most importantly, knowing what your audience hopes to learn from the document you are crafting will allow you to make sure that the information they need most is presented in a way that is easy for them to locate and understand.

Summary:
Consider your format. Create an outline. Set the tone. Address the audience's needs and objectives.