Make definite assertions. Avoid tame, colorless, hesitating, non-committal language. Use the word not as a means of denial or in antithesis, never as a means of evasion.
Read Elements of Style - some of the best programmers consider this to be one of the books which they always keep in arm's reach!
A few students are writing Google SoC reports; some are finding it difficult to express their ideas with clarity and precision. Reading this book will be of some help.
Here is what Richard Rogers has to say about good English (published in Jack Ganssle's Embedded Muse Newsletter ):
"When I interview a candidate for a firmware position, I try to assess his or her communication skills. A poorly written resume or cover letter raises an immediate red flag. A firmware engineer's job involves more than simply writing code. In-line comments, header blocks, design documents, technical manuals, project plans, product specifications, and even emails must all be clear and concise."