Always capitalize the personal pronoun I.
When writers wish to emphasize objectivity, as in formal academic and scientific writing, they avoid I and other first-person pronouns (such as my, we, our), often using passive voice constructions instead.
change I conducted the experiment . . .
to The experiment was conducted . . .
In much writing, however, and especially in expressive writing and some persuasive writing, I and other first-person pronouns are both natural and appropriate.
I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived. I did not wish to live what was not life, living is so dear, nor did I wish to practice resignation, unless it was quite necessary. I wanted to live deep and suck out all the marrow of life, to live so sturdily and Spartan-like as to put to rout all that was not life, to cut a broad swath and shave close, to drive life into a corner, and reduce it to its lowest terms, and, if it proved to be mean, why then to get the whole and genuine meanness of it, and publish its meanness to the world; or if it were sublime, to know it by experience, and be able to give a true account of it in my next excursion. — Henri
- David Thorkau, Waldcn
