Whenever possible, use strong subjects and active constructions, rather than weak verbal nouns or abstractions and weak passive or linking verbs: instead of "Petruchio's denial of Kate of her basic necessities would seem cruel and harsh...," try "By denying Kate the basic necessities of life, Petruchio appears cruel and harsh--but he says that he is just putting on an act." Don't forget that words and even phrases can serve as strong sentence subjects: "Petruchio's 'I'll buckler thee against a million' injects an unexpectedly chivalric note, especially since it follows hard on the heels of his seemingly un-gentlemanly behavior." And remember--use regular quotation marks unless you're quoting material that contains a quotation itself.
Use your best judgment on who you decide to ask - there is no set formula for who should be your recommenders. We know it is not always possible to have a direct supervisor write your recommendation – we would not want you to jeopardize your current position for the application process. Look at the questions we are asking recommenders to complete. Find people who know you well enough to answer them. This can be a former supervisor, a colleague, someone you collaborate on an activity outside of work. How well a person knows you should take priority over level of seniority or HBS alumni status.
Let me suggest one technique for starting a personal essay. Remember that for a story to be powerful and memorable for the reader, it must be powerful and memorable for the writer. So sit back and go down memory lane and make of list of those memories which stand out for you. They could be good or horrible. List the top 5 or 6 or 7 of these. Now look over each. Is there one that stands out as something which changed you? Or strengthened you? Or tested you? If so, that is your topic, and a description of that moment/incident/scene will become the first paragraph of your personal statement. The essay itself will then be your transition to a stronger you, a changed you, a you who has overcome some issue, nemesis, flaw, or challenge.