I almost always urge people to write in the first person. ... Writing is an act of ego and you might as well admit it.
William ZinsserEvery successful piece of nonfiction should leave the reader with one provocative thought that he or she didn't have before. Not two thoughts, or five - just one. So decide what single point you want to leave in the reader's mind.
William ZinsserMy commodity as a writer, whatever I'm writing about, is me. And your commodity is you. Don't alter your voice to fit the subject. Develop one voice that readers will recognize when they hear it on the page, a voice that's enjoyable not only in its musical line but in its avoidance of sounds that would cheapen its tone: breeziness and condescension and clichรฉs.
William Zinsser