How formal should you be? Is speaking in the first person acceptable? What are the textual conventions of your discipline? Are there any field-specific language expectations? More good questions and tough to answer: Despite how pervasively they affect everything in a given text, language-also known as text conventions-are difficult to generalize about since they involve matters of tone, style, organization and even, sometimes, sentence structure.
Although we all have our own personal style, we can't always write like we speak or in the way we feel most comfortable or in emulation of another. William Faulkner's style, for example, although admired by many, would sound absurd in a scientific article.
"Faulkner does Science": As the wisteria blooms over the Southern mansion where his father was born and from where his grandfather left to fight in the Civil War, I sit and write of chaos theory, an apt metaphor for much of what occurs in Yaknopitopwa County--the butterfly effect describing almost perfectly the confluence of history on the lives of everyday citizens in the present.
The best way to get a sense of what is expected is to read and analyze the writings of one or more professionals already publishing in the field of your study.
Note: One thing that can be generalized--addressing the audience in a casual, familiar manner, such as "you may think" or "as you may already know" is considered bad form in almost every academic argument. If you are unsure about this, ask your instructor.