Who will need to read what you've written? Will that reader be able to determine who wrote the stuff she is reading? Your audience, the who, affects the final how answer you'll need more than anything else on your list of preliminary, fact-finding questions.
Relax. That task of putting something in writing need not be as daunting as it first appears. After all, you've already defined your goal. Now all you need to do is establish the priorities necessary to reach the desired out-come: having something down on paper.
Determine Your Audience
Unless you're writing in your journal, where the only audience you please is yourself, the first fundamental question you'll need to answer is: Whom am I writing for? Once that is settled, you're ready to refine the scope even further by resolving these questions:
Does my reader already know me?
Is my reader somebody “in house” or will I be writing to somebody outside my center of influence?
Will my reader know anything about this topic?
Will my reader be receptive to what I'm writing, or will I need to include any special motivation for continuing?
Will I need to anticipate and overcome any objections or any ambivalence?
Establish the Voice for Your Writing
Next, you need to ask yourself: Who should the reader perceive as the author of this particular writing?
Should the author of the piece be invisible to the reader? If so, then first-person pronouns, such as I or we, should not be used.
Should the reader feel as if the author is speaking directly to him or her? If so, then you'll want to use the second person pronoun you a lot.
Should both the author and the reader be invisible? Then only third-person pronouns should be used, with no reference to I or you. This is the way most novels are written, with clear boundaries separating the reader from the piece, while also keeping the author invisible.